Bispecific chimeric antigen receptors and encoding polynucleotides thereof

ABSTRACT

The invention is directed to a bispecific chimeric antigen receptor, comprising: (a) at least two antigen-specific targeting regions; (b) an extracellular spacer domain; (c) a transmembrane domain; (d) at least one co-stimulatory domain; and (e) an intracellular signaling domain, wherein each antigen-specific targeting region comprises an antigen-specific single chain Fv (scFv) fragment, and binds a different antigen, and wherein the bispecific chimeric antigen receptor is co-expressed with a therapeutic control. The invention also provides methods and uses of the bispecific chimeric antigen receptors.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase of International ApplicationPCT/US2013/025953, filed Feb. 13, 2013, now expired, which designatedthe U.S. and that International Application was published under PCTArticle 21(2) in English. The present application also claims thebenefit of the filing date of U.S. Provisional Application No.61/598,216 filed Feb. 13, 2012, now expired, the disclosure of each ofwhich are incorporated herein by reference in their entirety.

FIELD OF INVENTION

The invention relates to chimeric antigen receptors and to geneticallyengineered cells using the same.

BACKGROUND OF THE INVENTION

Current immunotherapies are designed to target single antigens on cancercells. However, for example, cancer cells are unstable and some cellsmay no longer possess the target antigen. These cells, referred to asantigen loss escape variants, escape destruction by the therapy and maycontinue to grow and spread unchecked. Therefore there is a need in theart for therapies which prevent or minimize therapeutic failures incancer and other diseases.

SUMMARY OF THE INVENTION

In an embodiment, the invention provides a bispecific chimeric antigenreceptor, comprising (a) at least two antigen-specific targetingregions, (b) an extracellular spacer domain, (c) a transmembrane domain,(d) at least one co-stimulatory domain and (e) an intracellularsignaling domain, wherein each antigen-specific targeting regioncomprises an antigen-specific single chain Fv (scFv) fragment, and bindsa different antigen, and wherein the bispecific chimeric antigenreceptor is co-expressed with a therapeutic control.

In an embodiment, the invention further provides a combination of abispecific chimeric antigen receptor and a therapeutic control, whereinthe bispecific chimeric antigen receptor comprises (a) at least twoantigen-specific targeting regions, (b) an extracellular spacer domain,(c) a transmembrane domain, (d) at least one co-stimulatory domain and(e) an intracellular signaling domain, wherein each antigen-specifictargeting region comprises an antigen-specific single chain Fv (scFv)fragment, and binds a different antigen.

In an embodiment, the invention further provides a bispecific chimericantigen receptor, comprising (a) at least two antigen-specific targetingregions, (b) an extracellular spacer domain, (c) a transmembrane domain,(d) at least one co-stimulatory domain and (e) an intracellularsignaling domain, wherein each antigen-specific targeting regioncomprises an antigen-specific single chain Fv (scFv) fragment, and bindsa different antigen, and wherein the bispecific chimeric antigenreceptor is co-expressed with truncated epidermal growth factor receptor(EGFRt).

In an embodiment, the invention further provides a bispecific chimericantigen receptor, comprising (a) at least two antigen-specific targetingregions, (b) a CD8αhinge extracellular spacer domain, (c) a CD8αtransmembrane domain, (d) a 4-1BB co-stimulatory domain and (vi) a CD3zeta intracellular signaling domain, wherein each antigen-specifictargeting region comprises an antigen-specific single chain Fv (scFv)fragment, and binds a different antigen, wherein the bispecific chimericantigen receptor is co-expressed with EGFRt and wherein the bispecificchimeric antigen receptor and EGFRt are linked via a T2A linker.

In an embodiment, also provided are pharmaceutical compositionscomprising the above-described bispecific chimeric antigen receptors, acombination of the bispecific chimeric antigen receptors and therapeuticcontrols, polypeptides encoding the bispecific chimeric antigenreceptors, vectors, viruses and genetically engineered cells comprisingthe bispecific chimeric antigen receptors, vectors, viruses andgenetically engineered cells comprising a combination of the bispecificchimeric antigen receptors and therapeutic controls, or combinationsthereof, and a pharmaceutically acceptable carrier.

BRIEF DESCRIPTION OF FIGURES

Exemplary embodiments are illustrated in the referenced figures. It isintended that the embodiments and figures disclosed herein are to beconsidered illustrative rather than restrictive.

FIG. 1 depicts a schematic representation of a chimeric antigen receptorof the invention, in accordance with an embodiment of the presentinvention. ASTR is an antigen-specific targeting region, L is a linker,ESD is an extracellular spacer domain, TM is a transmembrane domain, CSDis a co-stimulatory domain, and ISD is an intracellular signalingdomain,

FIG. 2A-2B depict, (a) the components of an anti-CD19xCD20 CAR, and (b)a complete cDNA packaged into an epHIV-7 lentivirus vector transferplasmid, in accordance with an embodiment of the present invention.

FIG. 3 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid sequence of a bispecific CARCD19scFv-Gly4Ser1linker-CD20scFv-IgG4Hinge-CD28tm-41BB-CD3zeta-T2A-EGFRt_epHIV7 (SEQ ID NO: 1).

FIG. 4 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid and amino acid sequences of a bispecific CARCD19scFv-Gly4Ser1linker-CD20scFv-IgG4Hinge-CD28tm-41BB-CD3zeta-T2A-EGFRt_epHIV7(SEQ ID NO: 2).

FIG. 5 depicts, in accordance with an embodiment of the presentinvention, aCD19scFv-Gly4Ser1linker-CD20scFv-IgG4hinge-CD28tm-CD28gg-CD3Zetatransgene construct.

FIG. 6A-6B depict, in accordance with an embodiment of the presentinvention, development of a CγCR platform to support exogenous γcindependent growth. (a) Schematic diagrams of wild type versus chimericcytokine receptors. The IL-7Rα constitutive cytokine receptor (CγCR7)consists of the human IL-7 cytokine tethered to the full length humanIL-7Rα chain via a (G₄S)₂ linker. The IL-2Rβ constitutive cytokinereceptor (CγCR2) is identical to CγCR7 except that the IL-7Rαintracellular signaling domain is replaced with the human IL-2/IL-15βcytoplasmic domain. (b) Diagram of the expression constructCγCR-T2A-CD19t.

FIG. 7 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid and amino acid sequences of an embodiment ofthe invention, namely a backbone CAR comprising the hinge region ofIgG4, the transmembrane domain of CD28, the costimulatory domain of4-1BB and the cytoplasmic domain of CD3zeta (SEQ ID NO: 4 and SEQ ID NO:5).

FIG. 8 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid sequence of an embodiment of the invention,namelyGMCSFRss-CD19scFv-Gly4Serlinker-CD20scFv-huIgGHinge/CH2/CH3-CD28tm/CD28cyto-41BB-CD3zeta.GMCSFRss is the signal sequence from GMCSFR (SEQ ID NO: 7).

FIG. 9 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid and amino acid sequences of an embodiment ofthe invention, namelyGMCSFRss-CD19scFv-Gly4Serlinker-CD20scFv-huIgGHinge/CH2/CH3-CD28tm/CD28cyto-41BB-CD3zeta.GMCSFRss is the signal sequence from GMCSFR (SEQ ID NO: 8).

FIG. 10 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid sequence of an embodiment of the invention,namely theGMCSFRss-CD19scFv-Gly4Serlinker-CD20scFv-CD8αHinge-CD8αtm-41BB-CD3zeta-T2A-EGFRt(SEQ ID NO: 10). GMCSFRss is the signal sequence from GMCSFR. GMCSFRssis the signal sequence from GMCSFR.

FIG. 11 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid and amino acid sequences of an embodiment ofthe invention, namelyGMCSFRss-CD19scFv-Gly4Serlinker-CD20scFv-CD8αHinge-CD8αtm-41BB-CD3zeta-T2A-EGFRt(SEQ ID NO: 11). GMCSFRss is the signal sequence from GMCSFR.

FIG. 12 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid sequence of an embodiment of an inventionnamely T2A-EGFRt (SEQ ID NO: 13).

FIG. 13 depicts, in accordance with an embodiment of the presentinvention, the nucleic acid and amino acid sequences of an embodiment ofthe invention, namely T2A-EGFRt (SEQ ID NO: 14).

DETAILED DESCRIPTION OF THE INVENTION

All references cited herein are incorporated by reference in theirentirety as though fully set forth. Unless defined otherwise, technicaland scientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. Singleton et al., Dictionary of Microbiology and MolecularBiology 3^(rd) ed., J. Wiley & Sons (New York, N.Y. 2001); March,Advanced Organic Chemistry Reactions, Mechanisms and Structure 5^(th)ed., J. Wiley & Sons (New York, N.Y. 2001); and Sambrook and Russel,Molecular Cloning: A Laboratory Manual 3rd ed., Cold Spring HarborLaboratory Press (Cold Spring Harbor, N.Y. 2001), provide one skilled inthe art with a general guide to many of the terms used in the presentapplication.

One skilled in the art will recognize many methods and materials similaror equivalent to those described herein, which could be used in thepractice of the present invention. Indeed, the present invention is inno way limited to the methods and materials described. For purposes ofthe present invention, the following terms are defined below.

The invention described herein provides chimeric antigen receptors.Chimeric antigen receptors are engineered receptors which graft animmune specificity onto a genetically engineered cell. By housingspecificities to multiple antigens in a single chimeric antigen receptor(CAR), various benefits may be achieved, including, among others, asignificant reduction in effort as compared to making multiple T-cellproducts per patient.

Definitions

Components of the Chimeric Antigen Receptors

“Antigen-specific targeting region” (ASTR) as used herein refers to theregion of the CAR which targets specific antigens. The CARs of theinvention comprise at least two targeting regions which target at leasttwo different antigens. In an embodiment, CARs comprise three or moretargeting regions which target at least three or more differentantigens. The targeting regions on the CAR are extracellular. In someembodiments, the antigen-specific targeting regions comprise an antibodyor a functional equivalent thereof or a fragment thereof or a derivativethereof and each of the targeting regions target a different antigen.The targeting regions may comprise full length heavy chain, Fabfragments, single chain Fv (scFv) fragments, divalent single chainantibodies or diabodies, each of which are specific to the targetantigen. There are, however, numerous alternatives, such as linkedcytokines (which leads to recognition of cells bearing the cytokinereceptor), affibodies, ligand binding domains from naturally occurringreceptors, soluble protein/peptide ligand for a receptor (for example ona tumor cell), peptides, and vaccines to prompt an immune response,which may each be used in various embodiments of the invention. In fact,almost any molecule that binds a given antigen with high affinity can beused as an antigen-specific targeting region, as will be appreciated bythose of skill in the art.

“Chimeric antigen receptor” or “CAR” or “CARs” as used herein refers toengineered receptors, which graft an antigen specificity onto cells (forexample T cells such as naïve T cells, central memory T cells, effectormemory T cells or combination thereof). CARs are also known asartificial T-cell receptors, chimeric T-cell receptors or chimericimmunoreceptors. The CARs of the invention comprise at least twoantigen-specific targeting regions, an extracellular domain, atransmembrane domain, one or more co-stimulatory domains, and anintracellular signaling domain. The two or more antigen-specifictargeting regions target at least two different antigens and may bearranged in tandem and separated by linker sequences. In an embodiment,the extracellular spacer domain is optional. In another embodiment, theCAR is a bispecific CAR. A bispecific CAR is specific to two differentantigens.

“Co-stimulatory domain” (CSD) as used herein refers to the portion ofthe CAR which enhances the proliferation, survival and/or development ofmemory cells. The CARs of the invention may comprise one or moreco-stimulatory domains. Each co-stimulatory domain comprises thecostimulatory domain of any one or more of, for example, members of theTNFR superfamily, CD28, CD137 (4-1BB), CD134 (OX40), Dap10, CD27, CD2,CD5, ICAM-1, LFA-1 (CD11a/CD18), Lck, TNFR-I, TNFR-II, Fas, CD30, CD40or combinations thereof. Other co-stimulatory domains (e.g., from otherproteins) will be apparent to those of skill in the art and may be usedin connection with alternate embodiments of the invention.

“Extracellular spacer domain” (ESD) as used herein refers to thehydrophilic region which is between the antigen-specific targetingregion and the transmembrane domain. In some embodiments, the CARs ofthe invention comprise an extracellular spacer domain. In otherembodiments, the CARs of the invention do not comprise an extracellularspacer domain. The extracellular spacer domains include but are notlimited to Fc fragments of antibodies or fragments or derivativesthereof, hinge regions of antibodies or fragments or derivativesthereof, CH2 regions of antibodies, CH3 regions of antibodies,artificial spacer sequences or combinations thereof. Examples ofextracellular spacer domains include but are not limited to CD8α hinge,and artificial spacers made of polypeptides which may be as small as,for example, Gly3 or CH1 and CH3 domains of IgGs (such as human IgG4).In some embodiments, the extracellular spacer domain is any one or moreof (i) a hinge, CH2 and CH3 regions of IgG4, (ii) a hinge region ofIgG4, (iii) a hinge and CH2 of IgG4, (iv) a hinge region of CD8α, (v) ahinge, CH2 and CH3 regions of IgG1, (vi) a hinge region of IgG1 or (vi)a hinge and CH2 region of IgG1. Other extracellular spacer domains willbe apparent to those of skill in the art and may be used in connectionwith alternate embodiments of the invention.

“Intracellular signaling domain” (ISD) or “cytoplasmic domain” as usedherein refer to the portion of the CAR which transduces the effectorfunction signal and directs the cell to perform its specializedfunction. Examples of domains that transduce the effector functionsignal include but are not limited to the ζ chain of the T-cell receptorcomplex or any of its homologs (e.g., η chain, FcεR1γ and β chains, MB1(Igα) chain, B29 (Igβ) chain, etc.), human CD3 zeta chain, CD3polypeptides (Δ, δ and ε), syk family tyrosine kinases (Syk, ZAP 70,etc.), src family tyrosine kinases (Lck, Fyn, Lyn, etc.) and othermolecules involved in T-cell transduction, such as CD2, CD5 and CD28.Other intracellular signaling domains will be apparent to those of skillin the art and may be used in connection with alternate embodiments ofthe invention.

“Linker” (L) or “linker domain” or “linker region” as used herein referto an oligo- or polypeptide region from about 1 to 100 amino acids inlength, which links together any of the domains/regions of the CAR ofthe invention. Linkers may be composed of flexible residues like glycineand serine so that the adjacent protein domains are free to moverelative to one another. Longer linkers may be used when it is desirableto ensure that two adjacent domains do not sterically interfere with oneanother. Linkers may be cleavable or non-cleavable. Examples ofcleavable linkers include 2A linkers (for example T2A), 2A-like linkersor functional equivalents thereof and combinations thereof. In someembodiments, the linkers include the picornaviral 2A-like linker, CHYSELsequences of porcine teschovirus (P2A), Thosea asigna virus (T2A) orcombinations, variants and functional equivalents thereof. In otherembodiments, the linker sequences may compriseAsp-Val/Ile-Glu-X-Asn-Pro-Gly^((2A)-)pro^((2B)) motif, which results incleavage between the 2A glycine and the 2B proline. Other linkers willbe apparent to those of skill in the art and may be used in connectionwith alternate embodiments of the invention.

“Transmembrane domain” (TMD) as used herein refers to the region of theCAR which crosses the plasma membrane. The transmembrane domain of theCAR of the invention is the transmembrane region of a transmembraneprotein (for example Type I transmembrane proteins), an artificialhydrophobic sequence or a combination thereof. Other transmembranedomains will be apparent to those of skill in the art and may be used inconnection with alternate embodiments of the invention.

Others

“Antigen loss escape variants” as used herein refer to cells whichexhibit reduced or loss of expression of the target antigen, whichantigens are targeted by the CARs of the invention.

“B-cell associated diseases” as used herein include B-cellimmunodeficiencies, autoimmune diseases and/or excessive/uncontrolledcell proliferation associated with B-cells (including lymphomas and/orleukemias). Examples of such diseases, wherein bispecific CARs of theinvention may be used for therapeutic approaches include but are notlimited to systemic lupus erythematosus (SLE), diabetes, rheumatoidarthritis (RA), reactive arthritis, multiple sclerosis (MS), pemphigusvulgaris, celiac disease, Crohn's disease, inflammatory bowel disease,ulcerative colitis, autoimmune thyroid disease, X-linkedagammaglobulinaemis, pre-B acute lymphoblastic leukemia, systemic lupuserythematosus, common variable immunodeficiency, chronic lymphocyticleukemia, diseases associated with selective IgA deficiency and/or IgGsubclass deficiency, B lineage lymphomas (Hodgkin's lymphoma and/ornon-Hodgkin's lymphoma), immunodeficiency with thymoma, transienthypogammaglobulinaemia and/or hyper IgM syndrome, as well asvirally-mediated B-cell diseases such as EBV mediatedlymphoproliferative disease, and chronic infections in which B-cellsparticipate in the pathophysiology.

“Beneficial results” may include, but are in no way limited to,lessening or alleviating the severity of the disease condition,preventing the disease condition from worsening, curing the diseasecondition, preventing the disease condition from developing, loweringthe chances of a patient developing the disease condition and prolonginga patient's life or life expectancy.

“Cancer” and “cancerous” refer to or describe the physiologicalcondition in mammals that is typically characterized by unregulated cellgrowth. Examples of cancer include, but are not limited to B-celllymphomas (Hodgkin's lymphomas and/or non-Hodgkins lymphomas), braintumor, breast cancer, colon cancer, lung cancer, hepatocellular cancer,gastric cancer, pancreatic cancer, cervical cancer, ovarian cancer,liver cancer, bladder cancer, cancer of the urinary tract, thyroidcancer, renal cancer, carcinoma, melanoma, head and neck cancer, braincancer, and prostate cancer, including but not limited toandrogen-dependent prostate cancer and androgen-independent prostatecancer.

“Co-express” as used herein refers to simultaneous expression of two ormore genes. Genes may be nucleic acids encoding, for example, a singleprotein or a chimeric protein as a single polypeptide chain. Forexample, the CARs of the invention may be co-expressed with atherapeutic control (for example truncated epidermal growth factor(EGFRt)), wherein the CAR is encoded by a first polynucleotide chain andthe therapeutic control is encoded by a second polynucleotide chain. Inan embodiment, the first and second polynucleotide chains are linked bya nucleic acid sequence that encodes a cleavable linker Thepolynucleotides encoding the CAR and the therapeutic control system maybe linked by IRES sequences. Alternately, the CAR and the therapeuticcontrol are encoded by two different polynucleotides that are not linkedvia a linker but are instead encoded by, for example, two differentvectors. Further, the CARs of the invention may be co-expressed with atherapeutic control and CCR, a therapeutic control and DHFR (for examplemutant DHFR) or a therapeutic control and CCR and DHFR (for examplemutant DHFR). The CAR, therapeutic control and CCR may be co-expressedand encoded by first, second and third polynucleotide sequences,respectively, wherein the first, second and third polynucleotidesequences are linked via IRES sequences or sequences encoding cleavablelinkers. Alternately, these sequences are not linked via linkers butinstead are encoded via, for example, separate vectors. The CAR,therapeutic control and DHFR (for example mutant DHFR) may beco-expressed and encoded by first, second and fourth polynucleotidesequences, respectively, wherein the first, second and fourthpolynucleotide sequences are linked via IRES sequences or via sequencesencoding cleavable linkers. Alternately, these sequences are not linkedvia linkers but instead encoded via, for example, separate vectors. TheCAR, therapeutic control, CCR and DHFR (for example mutant DHFR) may beco-expressed and encoded by first, second, third and fourthpolynucleotide sequences, respectively, wherein the first, second, thirdand fourth polynucleotide sequences are linked via IRES sequences orsequences encoding cleavable linkers. Alternately, these sequences arenot linked via linkers but instead are encoded via, for example,separate vectors. If the aforementioned sequences are encoded byseparate vectors, these vectors may be simultaneously or sequentiallytransfected.

“Conditions”, “disease conditions,” “diseases” and “disease state” asused herein include physiological states in which diseased cells may betargeted with the CARs of the invention, expressing, for example,antibodies against specific antigens on the diseased cells. Examples ofantigens which may be targeted include but are not limited to antigensexpressed on B-cells (such as CD19 and CD20), antigens expressed oncarcinomas, sarcomas, lymphomas, leukemia, germ cell tumors, blastomas,antigens expressed on various immune cells, and antigens expressed oncells associated with various hematologic diseases, autoimmune diseases,and/or inflammatory diseases.

“Disease targeted by genetically modified cells” as used hereinencompasses the targeting of any cell involved in any manner in anydisease by the genetically modified cells of the invention, irrespectiveof whether the genetically modified cells target diseased cells orhealthy cells to effectuate a therapeutically beneficial result. Thegenetically modified cells include but are not limited to geneticallymodified T-cells, NK cells, hematopoietic stem cells, pluripotentembryonic stem cells or embryonic stem cells. The genetically modifiedcells express the CARs of the invention, which CARs may target any ofthe antigens expressed on the surface of target cells. Examples ofantigens which may be targeted include but are not limited to antigensexpressed on B-cells; antigens expressed on carcinomas, sarcomas,lymphomas, leukemia, germ cell tumors, and blastomas; antigens expressedon various immune cells; and antigens expressed on cells associated withvarious hematologic diseases, autoimmune diseases, and/or inflammatorydiseases. Other antigens that may be targeted will be apparent to thoseof skill in the art and may be targeted by the CARs of the invention inconnection with alternate embodiments thereof.

“Effector function” refers to the specialized function of adifferentiated cell. Effector function of a T-cell, for example, may becytolytic activity or helper activity including the secretion ofcytokines.

“Genetically modified cells”, “redirected cells”, “geneticallyengineered cells” or “modified cells” as used herein refer to cells thatexpress the CAR of the invention.

“Immune cell” as used herein refers to the cells of the mammalian immunesystem including but not limited to antigen presenting cells, B-cells,basophils, cytotoxic T-cells, dendritic cells, eosinophils,granulocytes, helper T-cells, leukocytes, lymphocytes, macrophages, mastcells, memory cells, monocytes, natural killer cells, neutrophils,phagocytes, plasma cells and T-cells.

“Immune response” as used herein refers to immunities including but notlimited to innate immunity, humoral immunity, cellular immunity,immunity, inflammatory response, acquired (adaptive) immunity,autoimmunity and/or overactive immunity.

“Mammal” as used herein refers to any member of the class Mammalia,including, without limitation, humans and nonhuman primates such aschimpanzees and other apes and monkey species; farm animals such ascattle, sheep, pigs, goats and horses; domestic mammals such as dogs andcats; laboratory animals including rodents such as mice, rats and guineapigs, and the like. The term does not denote a particular age or sex.Thus, adult and newborn subjects, as well as fetuses, whether male orfemale, are intended to be included within the scope of this term.

“Polynucleotide” as used herein includes but is not limited to DNA, RNA,cDNA (complementary DNA), mRNA (messenger RNA), rRNA (ribosomal RNA),shRNA (small hairpin RNA), snRNA (small nuclear RNA), snoRNA (shortnucleolar RNA), miRNA (microRNA), genomic DNA, synthetic DNA, syntheticRNA, and/or tRNA.

“Naked DNA” as used herein refers to DNA encoding a CAR cloned in asuitable expression vector in proper orientation for expression. Viralvectors which may be used include but are not limited SIN lentiviralvectors, retroviral vectors, foamy virus vectors, adeno-associated virus(AAV) vectors, hybrid vectors and/or plasmid transposons (for examplesleeping beauty transposon system) or integrase based vector systems.Other vectors that may be used in connection with alternate embodimentsof the invention will be apparent to those of skill in the art.

“Single chain variable fragment”, “single-chain antibody variablefragments” or “scFv” antibodies as used herein refer to forms ofantibodies comprising the variable regions of only the heavy and lightchains, connected by a linker peptide.

“Target cell” as used herein refers to cells which are involved in adisease and can be targeted by the genetically modified cells of theinvention (including but not limited to genetically modified T-cells, NKcells, hematopoietic stem cells, pluripotent stem cells, and embryonicstem cells). Other target cells will be apparent to those of skill inthe art and may be used in connection with alternate embodiments of theinvention.

The terms “T-cell” and “T-lymphocyte” are interchangeable and usedsynonymously herein. Examples include but are not limited to naïve Tcells, central memory T cells, effector memory T cells or combinationsthereof.

“Therapeutic agents” as used herein refers to agents that are used to,for example, treat, inhibit, prevent, mitigate the effects of, reducethe severity of, reduce the likelihood of developing, slow theprogression of and/or cure, a disease. Diseases targeted by thetherapeutic agents include but are not limited to carcinomas, sarcomas,lymphomas, leukemia, germ cell tumors, blastomas, antigens expressed onvarious immune cells, and antigens expressed on cells associated withvarious hematologic diseases, autoimmune diseases, and/or inflammatorydiseases.

“Therapeutic controls” as used herein refers to agents that regulatecell proliferation, facilitate cell selection (for example selectingcells which express the chimeric antigen receptors of the invention),facilitate cell tracking or a combination thereof. In one embodiment,regulating cell proliferation comprises up-regulating cell proliferationto promote cell propagation. In another embodiment, regulating cellproliferation comprises down-regulating cell proliferation so as toreduce or inhibit cell propagation. In some embodiments, the agents thatserve as therapeutic controls may promote enrichment of cells whichexpress the bispecific chimeric antigen receptors which may result in atherapeutic advantage.

“Transduction” as used herein refers to the introduction of a foreignnucleic acid into a cell using a viral vector.

“Transfection” as used herein refers to the introduction of a foreignnucleic acid into a cell using recombinant DNA technology. The term“transformation” means the introduction of a “foreign” (i.e. extrinsicor extracellular) gene, DNA or RNA sequence to a host cell, so that thehost cell will express the introduced gene or sequence to produce adesired substance, such as a protein or enzyme coded by the introducedgene or sequence. The introduced gene or sequence may also be called a“cloned” or “foreign” gene or sequence, may include regulatory orcontrol sequences, such as start, stop, promoter, signal, secretion, orother sequences used by a cell's genetic machinery. The gene or sequencemay include nonfunctional sequences or sequences with no known function.A host cell that receives and expresses introduced DNA or RNA has been“transformed” and is a “transformant” or a “clone.” The DNA or RNAintroduced to a host cell can come from any source, including cells ofthe same genus or species as the host cell, or cells of a differentgenus or species

“Treatment” and “treating,” as used herein refer to both therapeutictreatment and prophylactic or preventative measures, wherein the objectis to prevent or slow down (lessen) the targeted pathologic condition,prevent the pathologic condition, pursue or obtain beneficial results,or lower the chances of the individual developing the condition even ifthe treatment is ultimately unsuccessful. Those in need of treatmentinclude those already with the condition as well as those prone to havethe condition or those in whom the condition is to be prevented.

“Tumor,” as used herein refers to all neoplastic cell growth andproliferation, whether malignant or benign, and all pre-cancerous andcancerous cells and tissues.

“Vector”, “cloning vector” and “expression vector” as used herein referto the vehicle by which a polynucleotide sequence (e.g. a foreign gene)can be introduced into a host cell, so as to transform the host andpromote expression (e.g. transcription and translation) of theintroduced sequence. Vectors include plasmids, phages, viruses, etc.

Description Of The Invention

Chimeric Antigen Receptors

While not wishing to be limited by any one premise, it is believed thatthe chimeric antigen receptors (for example bispecific CARs) of theinstant invention may overcome conventional therapeutic failures due to,for example, outgrowth of antigen loss escape variants that can arise inthe course of various therapies when a single antigen is targeted.Accordingly, the invention is directed to, among other things, nucleicacid sequences and amino acid sequences encoding CARs, vectorscomprising CARs, viruses comprising CARs, genetically modified cellscomprising the CARs (redirected cells) and methods of making and usingthem. In some embodiments, the CARs are bispecific CARs. In otherembodiments, the CARs target and bind three or more different antigens.

In general embodiments, the present invention relates to CARs (forexample bispecific CARs), nucleic acid sequences encoding the CARs (forexample bispecific CARs), the vectors comprising the nucleic acidsencoding the CARs (for example bispecific CARs), viruses comprising thenucleic acid sequences encoding the CARs (for example bispecific CARs),host cells (such as genetically modified cells) expressing the CARs (forexample bispecific CARs), combinations of CARs (for example bispecificCARs) and therapeutic controls and methods of making and using the CARs(for example bispecific CARs) as therapeutic agents.

The CARs of the invention target at least two different antigens. TheCARs (such as bispecific CARs) are co-expressed with a therapeuticcontrol; for instance, truncated epidermal growth factor receptor(EGFRt), chimeric cytokine receptors (CCR) and/or dihydroxyfolatereceptor (DHFR) (e.g., mutant DHFR). The polynucleotides encoding theCAR and the therapeutic control(s) may be linked via IRES sequences orvia polynucleotide sequences encoding cleavable linkers. The CARs of theinvention are constructed so that they may be expressed in cells, whichin turn proliferate in response to the presence of at least one moleculethat interacts with at least one antigen-specific targeting region, forinstance, an antigen.

In some embodiments, therapeutic controls for use with the CARs of theinvention comprise any one or more of truncated epidermal growth factorreceptor (EGFRt), thymidine kinase, cytosine deaminase, nitroreductase,xanthine-guanine phosphoribosyl transferase, human caspase 8, humancaspase 9, purine nucleoside phosphorylase, linamarase/linamarin/glucoseoxidase, deoxyribonucleoside kinase, horseradish peroxidase(HRP)/indole-3-acetic (IAA), Gamma-glutamylcysteine synthetase,CD20/alphaCD20, CD34/thymidine kinase chimera, dox-depedent caspase-2,mutant thymidine kinase (HSV-TKSR39) or AP1903/Fas system. In anembodiment, the CARs of the invention are linked to EGFRt via acleavable linker or IRES sequences. In another embodiment, a bispecificCAR is linked to EGFRt via a cleavable linker or IRES sequences.

The CARs described herein may be synthesized as single polypeptidechains and may comprise at least two antigen-specific targeting regions,an extracellular spacer domain, a transmembrane domain, one or moreco-stimulatory domains and an intracellular signaling domain. In thisembodiment, the antigen-specific targeting regions are at theN-terminus, arranged in tandem and are separated by a linker peptide.The antigen-specific targeting region is linked to an extracellularspacer domain which is linked to the transmembrane domain. Thetransmembrane domain is linked to the co-stimulatory domain. Theco-stimulatory domain is linked to the intracellular signaling domainwhich is at the C-terminus. If more than one co-stimulatory domain isused, the multiple co-stimulatory domains may be arranged in tandem withthe transmembrane domain at its N-terminus and the intracellularsignaling domain at its C-terminus. Polynucleotides encoding thesepolypeptides may further comprise an N-terminal signal sequence whichdirects the CAR to the cell surface as a type I transmembrane protein.The antigen-specific targeting region may be extracellular-facing andthe intracellular signaling domain may be cytoplasmic.

FIG. 1 shows a schematic of a chimeric antigen receptor of theinvention.

In an embodiment, an extracellular spacer domain in the CAR is optional.In such a CAR, the antigen-specific targeting regions are at theN-terminus, arranged in tandem, and separated by a linker peptide. Theantigen-specific targeting region may be linked to the transmembranedomain. The transmembrane domain may be linked to the co-stimulatorydomain. The co-stimulatory domain may be linked to the intracellularsignaling domain, which is at the C-terminus. If more than oneco-stimulatory domain is used, the multiple co-stimulatory domains maybe arranged in tandem with the transmembrane domain at its N-terminusand the intracellular signaling domain at its C-terminus.Polynucleotides encoding these polypeptides may further comprise anN-terminal signal sequence which directs the CAR to the cell surface asa type I transmembrane protein. The antigen-specific targeting regionmay be extracellular-facing and the intracellular signaling domain maybe cytoplasmic.

Antigen-Specific Targeting Regions of Chimeric Antigen Receptors

The CARs of the invention may target several (such as two or more, threeor more) different antigens. In an embodiment, the CAR is a bispecificCAR and targets two different antigens. As described above, theantigen-specific targeting regions of the CAR may be arranged in tandemand may be separated by linker peptides. The antigens targeted by theCAR may be antigens on single diseased cell (such as a cancerous B-cell)or antigens that are expressed on separate cells that each contribute tothe disease. The antigens targeted by the CAR are antigens which areeither directly or indirectly involved in the disease.

In a bispecific CAR, at least two different antigen-specific antibodiesor fragments thereof or derivatives thereof may be cloned into theantigen-specific targeting region. The antibodies may be specific forany, but at least two, distinct antigens of choice. The antibodyspecific to the antigen may be the Fab fragment of the antibody or thesingle chain variable fragment (scFv) of the antibody.

For example, FIG. 2 shows an embodiment of the invention depicting a CARspecific to CD19 and CD20. Using methods well known to one skilled inthe art, scFvs specific to multiple, but at least two differentantigens, may be cloned upstream (i.e., to N-terminus) of theIgG₄-CD28-zeta domains so long as the target-antigens are expressed oncells that are targetable by the genetically modified cells describedbelow. Such techniques are explained fully in the literature. (Sambrooket al, “Molecular Cloning: A Laboratory Manual” (1989), CurrentProtocols in Molecular Biology. Volumes I-III [Ausubel, R. M., ed.(1994)], Cell Biology: A Laboratory Handbook. Volumes I-III [J. E.Celis, ed. (1994))], Current Protocols in Immunology. Volumes I-III[Coligan, J. E., ed. (1994)], Oligonucleotide Synthesis. (M. J. Gait ed.1984), Nucleic Acid Hybridization [B. D. Hames & S. J. Higgins eds.(1985)], Transcription And Translation [B. D. Hames & S. J. Higgins,eds. (1984)], Animal Cell Culture [R. I. Freshney, ed. (1986)],Immobilized Cells And Enzymes [IRL Press, (1986)], Practical Guide ToMolecular Cloning B. Perbal (1984), Current Prptocols in Immunology (J.E. Coligan, A. M. Kruisbeek, D. H. Margulies, E. M. Shevach and W.Strober, eds., 1991), Annual Review of Immunology as well as monographsin journals such as Advances in Immunology).

In one embodiment, each antigen-specific targeting region comprises thefull-length IgG heavy chain (specific for the target antigen) having theV_(H), CH1, hinge, and the CH2 and CH3 (Fc) Ig domains, if the V_(H)domain alone is sufficient to confer antigen-specificity (“single-domainantibodies”). The full length IgG heavy chain may be linked to theco-stimulatory domain and the intracellular signaling domain via theappropriate transmesmbrane domain. If both, the V_(H) and the V_(L)domains, are necessary to generate a fully active antigen-specifictargeting region, the V_(H)-containing CAR and the full-length lambdalight chain (IgL) are both introduced into the cells to generate anactive antigen-specific targeting region. In an embodiment, anextracelluar spacer domain may be linked between the antigen-specificbinding domain and the transmembrane domain. The cells include but arenot limited to T-lymphocytes (T-cells), natural killer cells,hematopoietic stem cells and/or pluripotent embryonic/induced stem cellscapable of giving rise to therapeutically relevant progeny.

In another embodiment, each antigen-specific targeting region of the CARcomprises at least two single chain antibody variable fragments (scFv),each specific for a different target antigen. scFvs, in which theC-terminus of one variable domain (V_(H) or V_(L)) is tethered to theN-terminus of the other (V_(L) or V_(H), respectively) via a polypeptidelinker, have been developed without significantly disrupting antigenbinding or specificity of the binding. (Chaudhary et al., A recombinantsingle-chain immunotoxin composed of anti-Tac variable regions and atruncated diphtheria toxin. 1990 Proc. Natl. Acad. Sci., 87:9491; Bedzyket al. Immunological and structural characterization of a high affinityanti-fluorescein single-chain antibody. 1990 J. Biol. Chem., 265:18615).The linker connects the N-terminus of the V_(H) with the C-terminus ofV_(L) or the C-terminus of V_(H) with the N-terminus of V_(L). ThesescFvs lack the constant regions (Fc) present in the heavy and lightchains of the native antibody. The scFvs, specific for at least twodifferent antigens, are arranged in tandem and linked to theco-stimulatory domain and the intracellular signaling domain via atransmembrane domain. In an embodiment, an extracelluar spacer domainmay be linked between the antigen-specific binding region and thetransmembrane domain.

In another aspect, each scFv fragment may be fused to all or a portionof the constant domains of the heavy chain. The resultingantigen-specific targeting region, specific for at least two differentantigens, is joined to the co-stimulatory domain and the intracellularsignaling domain via a transmembrane domain. In an embodiment, anextracelluar spacer domain may be linked between the antigen-specificbinding domain and the transmembrane domain.

In a further embodiment, each antigen-specific targeting region of theCAR comprises a divalent (or bivalent) single-chain variable fragment(di-scFvs, bi-scFvs). In CARs comprising di-scFVs, two scFvs specificfor each antigen are linked together by producing a single peptide chainwith two V_(H) and two V_(L) regions, yielding tandem scFvs. (Xiong,Cheng-Yi; Natarajan, A; Shi, X B; Denardo, G L; Denardo, S J (2006).“Development of tumor targeting anti-MUC-1 multimer: effects of di-scFvunpaired cysteine location on PEGylation and tumor binding”. ProteinEngineering Design and Selection 19 (8): 359-367; Kufer, Peter;Lutterbüse, Ralf; Baeuerle, Patrick A. (2004). “A revival of bispecificantibodies”. Trends in Biotechnology 22 (5): 238-244). CARs comprisingat least two antigen-specific targeting regions would express two scFvsspecific for each of the two antigens. The resulting antigen-specifictargeting region, specific for at least two different antigens, isjoined to the co-stimulatory domain and the intracellular signalingdomain via a transmembrane domain. In an embodiment, an extracelluarspacer domain may be linked between the antigen-specific binding domainand the transmembrane domain.

In an additional embodiment, each antigen-specific targeting region ofthe CAR comprises a diabody. In a diabody, the scFvs are created withlinker peptides that are too short for the two variable regions to foldtogether, driving the scFvs to dimerize. Still shorter linkers (one ortwo amino acids) lead to the formation of trimers, the so-calledtriabodies or tribodies. Tetrabodies may also be used.

To create the CARs of the present invention, two or more individualantigen-specific targeting regions are connected to each other, eithercovalently or noncovalently, on a single protein molecule. An oligo- orpolypeptide linker, an Fc hinge or membrane hinge region may be used toconnect these domains to each other. The CARs of the present inventionmay comprise two or more of the different antigen-specific targetingregions connected together in different combinations. For example, twoor more antigen-specific targeting regions containing immunoglobulinsequences (e.g. scFvs and/or single-domain antibodies) may be linked toeach other.

Targets of Antigen-Specific Targeting Regions of Chimeric AntigenReceptors

In some embodiments, the antigen-specific targeting region of the CAR(for example bispecific CAR) targets antigens specific for cancer,inflammatory disease, neuronal-disorders, diabetes, cardiovasculardisease, infectious diseases or a combination thereof. Examples ofantigens which may be targeted by the CARs (for example bispecific CARs)of the invention include but are not limited to antigens expressed onB-cells, antigens expressed on carcinomas, sarcomas, lymphomas,leukemia, germ cell tumors, blastomas, antigens expressed on variousimmune cells, and antigens expressed on cells associated with varioushematologic diseases, autoimmune diseases, and/or inflammatory diseases.The CARs of the invention, which are specific for at least two differenttarget antigens, may be capable of redirecting the effector function ofthe expressing-cells to either of both of the target antigens. Thisfeature of the construct may overcome the issue of antigen loss escapevariants when targeting, for example, genetically unstable B-celllineage malignancies using single antigen-specificity.

Antigens specific for cancer which may be targeted by the CARs (forexample bispecific CARs) of the invention include but are not limited toany one or more of 4-1BB, 5T4, adenocarcinoma antigen,alpha-fetoprotein, BAFF, B-lymphoma cell, C242 antigen, CA-125, carbonicanhydrase 9 (CA-IX), C-MET, CCR4, CD152, CD19, CD20, CD200, CD22, CD221,CD23 (IgE receptor), CD28, CD30 (TNFRSF8), CD33, CD4, CD40, CD44 v6,CD51, CD52, CD56, CD74, CD80, CEA, CNTO888, CTLA-4, DR5, EGFR, EpCAM,CD3, FAP, fibronectin extra domain-B, folate receptor 1, GD2, GD3ganglioside, glycoprotein 75, GPNMB, HER2/neu, HGF, human scatter factorreceptor kinase, IGF-1 receptor, IGF-I, IgG1, L1-CAM, IL-13, IL-6,insulin-like growth factor I receptor, integrin α5β1, integrin αvβ3,MORAb-009, MS4A1, MUC1, mucin CanAg, N-glycolylneuraminic acid, NPC-1C,PDGF-R α, PDL192, phosphatidylserine, prostatic carcinoma cells, RANKL,RON, ROR1, SCH 900105, SDC1, SLAMF7, TAG-72, tenascin C, TGF beta 2,TGF-β, TRAIL-R1, TRAIL-R2, tumor antigen CTAA16.88, VEGF-A, VEGFR-1,VEGFR2 or vimentin. Other antigens specific for cancer will be apparentto those of skill in the art and may be used in connection withalternate embodiments of the invention. Examples of CARs which targetthe above antigens include but are not limited to bispecific CARs,bispecific CARs co-expressed with EGFRt, bispecific CARs co-expressedwith EGFRt and CCR, bispecific CARs co-expressed with EGFRt and DHFR(for example mutant DHFR) or bispecific CARs co-expressed with EGFRt andCDR and DHFR (for example mutant DHFR).

In some embodiments, the bispecific chimeric antigen receptors targetand bind at least two different antigens. Examples of pairings of atleast two antigens bound by the bispecific CARs of the invention includebut are not limited to CD19 and CD20, CD19 and CD22, CD20 and L1-CAM,L1-CAM and GD2, EGFR and L1-CAM, EGFR and C-MET, EGFR and HER2, C-METand HER2 and EGFR and ROR1. Other pairings of antigens specific forcancer will be apparent to those of skill in the art and may be used inconnection with alternate embodiments of the invention. In yet otherembodiments, the bispecific chimeric antigen receptor targets CD19 andCD20. Examples of CARs which target the above antigens include but arenot limited to bispecific CARs, bispecific CARs co-expressed with EGFRt,bispecific CARs co-expressed with EGFRt and CCR, bispecific CARsco-expressed with EGFRt and DHFR (for example mutant DHFR) or bispecificCARs co-expressed with EGFRt and CDR and DHFR (for example mutant DHFR).

Antigens specific for inflammatory diseases which may be targeted by theCARs of the invention include but are not limited to any one or more ofAOC3 (VAP-1), CAM-3001, CCL11 (eotaxin-1), CD125, CD147 (basigin), CD154(CD40L), CD2, CD20, CD23 (IgE receptor), CD25 (α chain of IL-2receptor), CD3, CD4, CD5, IFN-α, IFN-γ, IgE, IgE Fc region, IL-1, IL-12,IL-23, IL-13, IL-17, IL-17A, IL-22, IL-4, IL-5, IL-5, IL-6, IL-6receptor, integrin α4, integrin α4β7, Lama glama, LFA-1 (CD11 a),MEDI-528, myostatin, OX-40, rhuMAb β7, scleroscin, SOST, TGF beta 1,TNF-α or VEGF-A. Other antigens specific for inflammatory diseases willbe apparent to those of skill in the art and may be used in connectionwith alternate embodiments of the invention. Examples of CARs whichtarget the above antigens include but are not limited to bispecificCARs, bispecific CARs co-expressed with EGFRt, bispecific CARsco-expressed with EGFRt and CCR, bispecific CARs co-expressed with EGFRtand DHFR (for example mutant DHFR) or bispecific CARs co-expressed withEGFRt and CDR and DHFR (for example mutant DHFR).

Antigens specific for neuronal disorders which may be targeted by theCARs of the invention include but are not limited to any one or more ofbeta amyloid or MABT5102A. Other antigens specific for neuronaldisorders will be apparent to those of skill in the art and may be usedin connection with alternate embodiments of the invention. Examples ofCARs which target the above antigens include but are not limited tobispecific CARs, bispecific CARs co-expressed with EGFRt, bispecificCARs co-expressed with EGFRt and CCR, bispecific CARs co-expressed withEGFRt and DHFR (for example mutant DHFR) or bispecific CARs co-expressedwith EGFRt and CDR and DHFR (for example mutant DHFR).

Antigens specific for diabetes which may be targeted by the CARs of theinvention include but are not limited to any one or more of L-1β or CD3.Other antigens specific for diabetes or other metabolic disorders willbe apparent to those of skill in the art and may be used in connectionwith alternate embodiments of the invention. Examples of CARs whichtarget the above antigens include but are not limited to bispecificCARs, bispecific CARs co-expressed with EGFRt, bispecific CARsco-expressed with EGFRt and CCR, bispecific CARs co-expressed with EGFRtand DHFR (for example mutant DHFR) or bispecific CARs co-expressed withEGFRt and CDR and DHFR (for example mutant DHFR).

Antigens specific for cardiovascular diseases which may be targeted bythe CARs of the invention include but are not limited to any one or moreof C5, cardiac myosin, CD41 (integrin alpha-IIb), fibrin II, beta chain,ITGB2 (CD18) and sphingosine-1-phosphate. Other antigens specific forcardiovascular diseases will be apparent to those of skill in the artand may be used in connection with alternate embodiments of theinvention. Examples of CARs which target the above antigens include butare not limited to bispecific CARs, bispecific CARs co-expressed withEGFRt, bispecific CARs co-expressed with EGFRt and CCR, bispecific CARsco-expressed with EGFRt and DHFR (for example mutant DHFR) or bispecificCARs co-expressed with EGFRt and CDR and DHFR (for example mutant DHFR).

Antigens specific for infectious diseases which may be targeted by theCARs of the invention include but are not limited to any one or more ofanthrax toxin, CCR5, CD4, clumping factor A, cytomegalovirus,cytomegalovirus glycoprotein B, endotoxin, Escherichia coli, hepatitis Bsurface antigen, hepatitis B virus, HIV-1, Hsp90, Influenza Ahemagglutinin, lipoteichoic acid, Pseudomonas aeruginosa, rabies virusglycoprotein, respiratory syncytial virus and TNF-α. Other antigensspecific for infectious diseases will be apparent to those of skill inthe art and may be used in connection with alternate embodiments of theinvention. Examples of CARs which target the above antigens include butare not limited to bispecific CARs, bispecific CARs co-expressed withEGFRt, bispecific CARs co-expressed with EGFRt and CCR, bispecific CARsco-expressed with EGFRt and DHFR (for example mutant DHFR) or bispecificCARs co-expressed with EGFRt and CDR and DHFR (for example mutant DHFR).

Further examples of target antigens include but are not limited tosurface proteins found on cancer cells in a specific or amplifiedfashion (e.g. the IL-14 receptor, CD19, CD20 and CD40 for B-celllymphoma, the Lewis Y and CEA antigens for a variety of carcinomas, theTag72 antigen for breast and colorectal cancer, EGF-R for lung cancer,folate binding protein and the HER-2 protein which is often amplified inhuman breast and ovarian carcinomas), or viral proteins (e.g. gp120 andgp41 envelope proteins of HIV, envelope proteins from the Hepatitis Band C viruses, the glycoprotein B and other envelope glycoproteins ofhuman cytomegalovirus, the envelope proteins from oncoviruses such asKaposi's sarcoma-associated Herpes virus). Other potential targets ofthe CARs of the invention include CD4, where the ligand is the HIV gp120envelope glycoprotein, and other viral receptors, for example ICAM,which is the receptor for the human rhinovirus, and the related receptormolecule for poliovirus.

Additional targets of the CARs of the invention include antigensinvolved in B-cell associated diseases. Yet further targets of the CARsof the invention will be apparent to those of skill in the art and maybe used in connection with alternate embodiments of the invention.

Co-Stimulatory Domains of Chimeric Antigen Receptors

The CARs of the invention may also comprise a co-stimulatory domain.This domain may enhance cell proliferation, cell survival anddevelopment of memory cells. The CARs of the invention may comprise oneor more co-stimulatory domains. Each co-stimulatory domain comprises theco-stimulatory domain of any one or more of, for example, members of theTNFR super family, CD28, CD137 (4-1BB), CD134 (OX40), Dap10, CD27, CD2,CD5, ICAM-1, LFA-1, Lck, TNFR-1, TNFR-II, Fas, CD30, CD40 orcombinations thereof. Co-stimulatory domains from other proteins mayalso be used with the CARs of the invention. Additional co-stimulatorydomains will be apparent to those of skill in the art and may be used inconnection with alternate embodiments of the invention. If a CARcomprises more than one co-stimulatory domain, these domains may bearranged in tandem, optionally separated by a linker.

Extracellular Spacer Domain of Chimeric Antigen Receptor

The CARs of the invention may further comprise an extracellular spacerdomain. In some embodiments, this domain facilitates proper proteinfolding. The extracellular spacer domain comprises a hydrophilic regionwhich is attached to the antigen-specific targeting region and thetransmembrane domain. Extracellular spacer domains may include, but arenot limited to, Fc fragments of antibodies or fragments or derivativesthereof, hinge regions of antibodies or fragments or derivativesthereof, CH2 regions of antibodies, CH3 regions antibodies, artificialspacer sequences or combinations thereof. Examples of extracellularspacer domains include but are not limited to CD8α hinge, artificialspacers made of polypeptides such as Gly3, or CH1, CH3 domains of IgG's(such as human IgG4). Specifically, the extracellular spacer domain maybe (i) a hinge, CH2 and CH3 regions of IgG4, (ii) a hinge region ofIgG4, (iii) a hinge and CH2 of IgG4, (iv) a hinge region of CD8α, (v) ahinge, CH2 and CH3 regions of IgG1, (vi) a hinge region of IgG1 or (vi)a hinge and CH2 of IgG1 or a combination thereof. Additionalextracellular spacer domains will be apparent to those of skill in theart and may be used in connection with alternate embodiments of theinvention.

Transmembrane Domain of Chimeric Antigen Receptors

The CARs of the invention may also comprise a transmembrane domain. Thetransmembrane domain may comprise the transmembrane sequence from anyprotein which has a transmembrane domain, including any of the type I,type II or type III transmembrane proteins. The transmembrane domain ofthe CAR of the invention may also comprise an artificial hydrophobicsequence. The transmembrane domains of the CARs of the invention may beselected so as not to dimerize. Additional transmembrane domains will beapparent to those of skill in the art and may be used in connection withalternate embodiments of the invention.

Intracellular Signaling Domain of Chimeric Antigen Receptors

The CARs of the invention may also comprise an intracellular signalingdomain. This domain may be cytoplasmic and may transduce the effectorfunction signal and direct the cell to perform its specialized function.Examples of intracellular signaling domains include, but are not limitedto, ζ chain of the T-cell receptor or any of its homologs (e.g., ηchain, FcεR1γ and β chains, MB1 (Igα) chain, B29 (Ig(β) chain, etc.),CD3 polypeptides (Δ, δ and ε), syk family tyrosine kinases (Syk, ZAP 70,etc.), src family tyrosine kinases (Lck, Fyn, Lyn, etc.) and othermolecules involved in T-cell transduction, such as CD2, CD5 and CD28.Specifically, the intracellular signaling domain may be human CD3 zetachain, FcγRIII, FcεRI, cytoplasmic tails of Fc receptors, immunoreceptortyrosine-based activation motif (ITAM) bearing cytoplasmic receptors orcombinations thereof. Additional intracellular signaling domains will beapparent to those of skill in the art and may be used in connection withalternate embodiments of the invention.

Linkers in Chimeric Antigen Receptors

In some embodiments, two or more components of the CARs of the inventionare separated by one or more linkers. For example, in CARs comprising atleast two antigen-specific targeting regions, the first targeting regionon the CAR may be separated from the second targeting region on the CARvia a linker. Additionally, the CAR may be linked to therapeuticcontrols via a linker. Linkers are oligo- or polypeptides region fromabout 1 to 100 amino acids in length, that link together any of thedomains/regions of the CAR of the invention. In some embodiments, thelinkers may be for example, 5-12 amino acids in length, 5-15 amino acidsin length or 5 to 20 amino acids in length. Linkers may be composed offlexible residues like glycine and serine so that the adjacent proteindomains are free to move relative to one another. Longer linkers, forexample those longer than 100 amino acids, may be used in connectionwith alternate embodiments of the invention, and may be selected to, forexample, ensure that two adjacent domains do not sterically interferewith one another. Examples of linkers which may be used in the instantinvention include but are not limited to 2A linkers (for example T2A),2A-like linkers or functional equivalents thereof.

Therapeutic Controls

Therapeutic controls regulate cell proliferation, facilitate cellselection (for example selecting cells which express the chimericantigen receptors of the invention) or a combination thereof. In oneembodiment, regulating cell proliferation comprises up-regulating cellproliferation to promote cell propagation. In another embodiment,regulating cell proliferation comprises down-regulating cellproliferation so as to reduce or inhibit cell propagation. In someembodiments, the agents that serve as therapeutic controls may promoteenrichment of cells which express the bispecific chimeric antigenreceptors which may result in a therapeutic advantage. In someembodiments, agents which serve as therapeutic controls maybiochemically interact with additional compositions so as to regulatethe functioning of the therapeutic controls. For example, EGFRt (atherapeutic control) may biochemically interact with cetuximab so as toregulate the function of EGFRt in selection, tracking, cell ablation ora combination thereof.

Examples of therapeutic controls include but are not limited to any oneor more of truncated epidermal growth factor receptor (EGFRt), thymidinekinase, cytosine deaminase, nitroreductase, xanthine-guaninephosphoribosyl transferase, human caspase 8, human caspase 9, purinenucleoside phosphorylase, linamarase/linamarin/glucose oxidase,deoxyribonucleoside kinase, horseradish peroxidase (HRP)/indole-3-acetic(IAA), Gamma-glutamylcysteine synthetase, CD20/alphaCD20, CD34/thymidinekinase chimera, dox-depedent caspase-2, mutant thymidine kinase(HSV-TKSR39), AP1903/Fas system, a chimeric cytokine receptor (CCR), aselection marker, and combinations thereof. In some embodiments, thetherapeutic controls are co-expressed with the bispecific chimericantigen receptor.

Examples of agents which regulate the functioning of the therapeuticcontrols include but are not limited to any one or more of Herceptin,methotrexate, cetuximab, thymidine analogs (for example ganciclovir),(E)-5-(2-bromovinyl)-2′-deoxyuridine (BVDU), 5-flurocytosine (5-FC), 5-(azaridin-1-yl)-2,4-dinitrob enzamide (CB1954), 6-thioguanine, asynthetic dimerizing drug (for example AP1903), fludarabine phosphate,linamarin (lin), nucleoside analogs (for example BVDU,difluorodeoxycytidine (dFdC), 1-β-D-arabinofuranosylthymine (ara-T)),indole-3-acetic (IAA), 1-buthionine-S,R-sulfoximine (BSO), rituximab(RTX), doxycycline, tyrosine kinase inhibitors or combinations thereof.These agents may be administered before, during or after the use of thetherapeutic controls.

As described above, the CARs of the invention may be synthesized assingle polypeptide chains. If the CAR is a bispecific CAR, thepolynucleotide sequence encoding the CAR may be, for example, in thefollowing configuration in the N-terminal to C-terminal direction:N-terminal signal sequence—antigen-specific targeting region1—linker—antigen-specific targeting region2—extracellular spacerdomain—transmembrane domain—co-stimulatory domain—intracellularsignaling domain. In an embodiment, such a CAR may comprise two or moreco-stimulatory domains.

Alternatively, the polynucleotide sequence encoding the CAR may be inthe following configuration in the N-terminal to C-terminal direction:N-terminal signal sequence—antigen-specific targeting region1—linker—antigen-specific targeting region 2—transmembranedomain—co-stimulatory domain—intracellular signaling domain. In anembodiment, such a CAR may comprise two or more co-stimulatory domains.

If a CAR comprises more than two antigen-specific targeting regions, thepolynucleotide sequence encoding the CAR may be in the followingconfiguration in the N-terminal to C-terminal direction: N-terminalsignal sequence—antigen-specific targeting region1—linker—antigen-specific targeting region 2—linker—(antigen-specifictargeting region)_(n)—transmembrane domain—co-stimulatorydomain—intracellular signaling domain. Such a CAR may further comprisean extracellular spacer domain. Each antigen-specific targeting regionmay be separated by a linker. In an embodiment, such a CAR may comprisetwo or more co-stimulatory domains.

The invention provides a nucleic acid sequence of the backbone of anexemplary CAR of the invention comprising an extracellular spacerdomain, a transmembrane domain, a co-stimulatory domain and anintracellular signaling domain. Specifically, an exemplary backbone fora may CAR comprise, in the N-terminus to C-terminus orientation,IgG4hinge-CD28tm-41BB-CD3zeta, wherein the extracellular spacer domainis the IgG4 hinge region, the transmembrane domain is the transmembraneregion from CD28, the co-stimulatory domain is from 4-1BB and theintracellular signaling domain is from the CD3 zeta chain (FIG. 7). Atleast two or more antigen-specific targeting regions may be insertedN-terminal to the IgG4 hinge.

The invention provides nucleic acid sequences of an exemplary embodimentof the invention where the CAR is specific to CD19 and CD20. In oneembodiment, the sequence encoding a bispecific anti-CD19xCD20 CAR is setforth in FIG. 3, 8 or 10. In another embodiment, the sequence encoding abispecific anti-CD19xCD20 CAR is set forth in FIG. 4, 9 or 11. In thisexemplary embodiment, the bispecific CAR comprises scFvs specific forCD19 and CD20 with each scFv separated by a linker, joined to anextracellular spacer domain, which is joined to the co-stimulatory andintracellular signaling domains via a transmembrane domain. Although theexemplary CAR depicts a set of scFv sequences, any scFv specific forCD19 and CD20 may be used. In a particular embodiment, the bispecificCAR specific for CD19 and CD20 isCD19scFv-Gly4Serlinker-CD20scFv-IgG4-Hinge-CD28tm-41BB(cyto)-zeta(cyto)and is encoded by the sequences set forth in FIGS. 3 and 4. Thisbispecific CAR comprises single chain Fv fragments specific for CD19 andCD20 linked by a Gly4Ser linker, an IgG4 hinge extracellular spacerdomain, a CD28 transmembrane domain, a 41BB costimulatory domain and thecytoplasmic domain from CD3 zeta chain.

In another embodiment, the bispecific CAR specific for CD19 and CD20comprisesCD19scFv-Gly4serlinker-CD20scFv-hulgG4-hingeCH2CH3-CD28tm/cyto-41BB-zeta(FIGS. 9-10). This bispecific CAR comprises single chain Fv fragmentsspecific for CD19 and CD20 linked by a Gly4Ser linker, a human IgG4hinge, CH2 and CH3 extracellular spacer domain, a CD28 transmembranedomain, a 4-1BB costimulatory domain and the cytoplasmic domain from CD3zeta chain.

In a further embodiment, the bispecific CAR specific for CD19 and CD20is CD19-Gly4serlinker-CD20scFv-CD8αhinge-CD8αTM-41BBcostim-zetacyto(FIGS. 11-12). This bispecific CAR comprises single chain Fv fragmentsspecific for CD19 and CD20 linked by a Gly4Ser linker, a CD8alpha hingeextracellular spacer domain, a CD8alpha transmembrane domain, a 41BBcostimulatory domain and the cytoplasmic domain from CD3 zeta chain.

Truncated Epidermal Growth Factor Receptor (EGFRt)

Human epidermal growth factor receptor (huEGFR) (EGFR; ErbB-1, HER1 inhumans) is a receptor tyrosine kinase of the ErbB family of growthfactor receptors that is not expressed by cells of the hematopoietic andlymphopoietic systems. Ligand (EGF, TGF-α) binding occurs withinN-terminal extracellular domains I and II of EGFR resulting fromtransition of receptor tyrosine kinase inactive monomers to activehomodimers.

Extracellular domain III of EGFR contains the binding sites ofantibodies (for example cetuximab (Erbitux), an IgG1 chimeric antibody).It is believed that human EGFR may be rendered incapable of bindingligands (EGF, TGF-α) by removal of domains I and II, and devoid ofsignaling activity by deletion of its cytoplasmic tail, while retainingan intact antibody binding site (for example cetuximab binding site),for example in extracellular domain III, IV or a combination thereof(Wang et al., A transgene-encoded cell surface polypeptide forselection, in vivo tracking, and ablation of engineered cells Blood118(5)1255-1263).

A truncated EGFRt polypeptide described herein has at least three usesfor genetic engineering of cell-based therapies: ex vivo cellpurification, in vivo cell tracking, and cell ablation. In anembodiment, EGFRt, for use as a therapeutic control with the CARs of theinvention, binds any one or more of EGFR-specific siRNA, a smallmolecule that targets EGFR, an anti-EGFR-antibody or a combinationthereof. In another embodiment, EGFRt comprises the sequence set forthin FIG. 12 or 13 or sequences that are about 70%, about 75%, about 80%,about 85%, about 90% or about 95% homologous to the sequences set forthin FIG. 12 or 13.

In an embodiment of the invention, huEGFRt may be co-expressed with theCARs of the invention so as to purify cells expressing the CARs (forexample ex vivo cell purification), track cells (for example in vitro orin vivo cell tracking) expressing the CARs or regulate cells (forexample in vivo or in vitro or ex vivo) expressing the CARs bytriggering cell ablation as required. In one embodiment, the CARs arebispecific CARs.

Chimeric Cytokine Receptor (CCR)

Based on the limitations of using exogenous γc cytokines in adoptiveimmunotherapy, the invention provides T cells with an intrinsic γccytokine signaling mechanism. The utility of forced constitutivechimeric cytokine receptors IL-2/IL-15Rβ (CγCR2) and IL-7Rα (CγCR7)receptor signals were compared. As described below, the chimericcytokine receptors have the ability to improve the survival,persistence, and in vivo engraftment of cytotoxic T cells (CTLs).

Accordingly, in an embodiment of the invention, the CARs of theinvention may be co-expressed with CCR. For example, a bispecific CARmay be co-expressed with EGFRt and CCR. Alternately, a bispecific CARmay be co-expressed with CCR. Examples of chimeric cytokine receptorinclude but are not limited to IL-7 cytokine-linker-IL7Rα, IL-7cytokine-linker-extracellular domain of IL-7Rα-transmembrane domain ofIL-7Rα-cytoplasmic domain of IL-2Rβ, IL-7 cytokine-linker-IL2Rβ.

A CCR comprising IL-7 cytokine-linker-IL7Rα comprises an N-terminalsignal sequence joined to the N-terminus of the IL-7 cytokine which islinked via a linker to extracellular, transmembrane and cytoplasmicdomains of IL-7Rα (the alpha chain of the IL-7 receptor).

A CCR comprising IL-7 cytokine-linker-extracellular domain ofIL-7Rα-transmembrane domain of IL-7Rα-cytoplasmic domain of IL-2Rβcomprises an N-terminal signal sequence joined to the N-terminus of theIL-7 cytokine which is linked via a linker to the extracellular domainand transmembrane domain of IL-7Rα and to the cytoplasmic domain ofIL-2Rβ (the beta chain of the IL-2 receptor).

A CCR comprising IL-7 cytokine-linker-IL2Rβ comprises N-terminal signalsequence joined to the N-terminus of the IL-7 cytokine which is linkedvia a linker to extracellular, transmembrane and cytoplasmic domains ofIL-2Rβ.

Dihydroxyfolate Receptor (DHFR)

Genetic modification of T cells to co-express a therapeutic transgeneand a drug resistant transgene that confers resistance to lymphotoxicdrugs provides the opportunity to select for therapeutic cells both invivo and ex vivo. A mutated human enzyme transgene, dihydrofolatereductase double mutant (DHFR^(FS); L22F, F31S), which confersresistance of engineered T cells to methotrexate (MTX), allowingselection of cells co-expressing a CD19-specific chimeric antigenreceptor (CD19CAR) that specifically targets B-lineage tumor cells.

In an embodiment, the CARs of the invention (for example bispecificCARs) may be co-expressed with DHFR (for example mutant DHFR). In afurther embodiment, the bispecific CAR may be co-expressed with EGFRt,CCR and DHFR (including mutant DHFR). Alternately, the bispecific CARmay be co-expressed with EGFRt and DHFR (including mutant DHFR).

Other selection markers that may be used with the CARs of the inventioninclude but are not limited to methylated-DNA-protein-cysteinemethyltransferase (MDMT), inosine monophosphate dehydrogenase II(IMDHP2) or a combination thereof. MDMT makes cells resistant tochemotherapy and therefore may be used if synergy between chemotherapyand T cell therapy is desired.

Vectors encoding the CARs of the invention are also provided herein.Vectors encoding CARs also encode EGFRt. In some embodiments, vectorsencoding CARs and EGFRt also encode CCR or DHFR (for example mutantDHFR). In other embodiments, vectors encoding CARs and EGFRt also encodeCCD and DHFR (for example mutant DHFR). In some specific embodiments,the vectors may encode a bispecific CAR and EGFRt, a bispecific CAR andEGFRt and CCR, a bispecific CAR and EGFRt and DHFR (for example mutantDHFR) or a bispecific CAR and EGFRt and CCR and DHFR (for example mutantDHFR). Vectors which may be used to express the CARs of the inventioninclude but are not limited to lentivirus vectors, gamma retrovirusvectors, foamy virus vectors, AAV vectors, adeno virus vectors,engineered hybrid viruses, naked DNA (including but not limited totransposon mediated vectors, such as Sleeping Beauty, Piggybak, andIntegrases such as Phi31.

In an exemplary embodiment of the invention, the bisepcific CAR specificto CD19 and CD20 disclosed herein is expressed via a lentiviral vectoras illustrated in FIG. 5.

Genetically Engineered Cells of the Invention

The invention also provides genetically engineered cells which compriseand stably express the CAR of the invention. The CAR expressed by thegenetically engineered cell may comprise at least two antigen-specifictargeting regions, an extracellular domain, a transmembrane domain, oneor more co-stimulatory domains and an intracellular signaling domain.The polynucleotide sequence encoding the CAR may also comprise anN-terminal signal sequence. In an embodiment, the CAR is a bispecificCAR. Each of the at least two antigen-specific targeting regions,extracellular spacer domain, transmembrane domain, one or moreco-stimulatory domains and an intracellular signaling domain aredescribed above. The antigen-specific targeting domains may be capableof specifically binding, in an MHC unrestricted manner, an antigen whichis not normally bound by a T-cell receptor in that manner.

In an embodiment, the genetically engineered cells that express the CARs(for example bispecific CARs) of the invention co-express EGFRt. In afurther embodiment, the genetically engineered cells that express theCARs (for example bispecific CARs) co-express EGFRt and CCR. In anadditional embodiment, the genetically engineered cells that express theCARs (for example bispecific CARs) co-express EGFRt and DHFR (forexample mutant DHFR). In another embodiment, the genetically engineeredcells that express the CARs (for example bispecific CARs) co-expressEGFRt, CCR and DHFR (for example mutant DHFR).

The genetically engineered cells express a CAR having at least twoantigen-specific targeting regions which are specific for at least twodifferent target antigens. In one embodiment, the antigen-specifictargeting regions comprise target-specific antibodies or functionalequivalents or fragments or derivatives thereof. The antigen-specificantibody may be the Fab fragment of the antibody or the single chainvariable fragment (scFv) of the antibody.

Genetically engineered cells which may comprise and express the CARs ofthe invention include, but are not limited to, T-lymphocytes (T-cells),naïve T cells (T_(N)), memory T cells (for example, central memory Tcells (T_(CM)), effector memory cells (T_(EM))), natural killer cells,hematopoietic stem cells and/or pluripotent embryonic/induced stem cellscapable of giving rise to therapeutically relevant progeny. In anembodiment, the genetically engineered cells are autologous cells. Byway of example, individual T-cells of the invention may be CD4+/CD8−,CD4−/CD8+, CD4−/CD8− or CD4+/CD8+. The T-cells may be a mixed populationof CD4+/CD8− and CD4−/CD8+ cells or a population of a single clone. CD4+T-cells of the invention may produce IL-2, IFNγ, TNFα and other T-celleffector cytokines when co-cultured in vitro with cells expressing thetarget antigens (for example CD20+ and/or CD19+ tumor cells). CD8⁺T-cells of the invention may lyse antigen-specific target cells whenco-cultured in vitro with the target cells. In some embodiments, T cellsmay be any one or more of CD45RA⁺ CD62L⁺ naïve cells, CD45RO⁺ CD62L⁺central memory cells, CD62L⁻ effector memory cells or a combinationthereof (Berger et al., Adoptive transfer of virus-specific andtumor-specific T cell immunity. Curr Opin Immunol 2009 21(2)224-232).

Genetically modified cells may be produced by stably transfecting cellswith DNA encoding the CAR of the invention. DNA encoding the CAR of theinvention (for example bispecific CAR) may also encode EGFRt, CCR and/orDHFR (for example mutant DHFR). In one embodiment, a firstpolynucleotide encodes the CAR (for example bispecific CAR) and islinked via IRES sequences or a polynucleotide that encodes a cleavablelinker, to a second polynucleotide that encodes EGFRt. In anotherembodiment, the first polynucleotide encodes the CAR (for examplebispecific CAR) and is linked via IRES sequences or a polynucleotidethat encodes a cleavable linker, to a second polynucleotide that encodesEGFRt and the first or second polynucleotides are linked to a thirdpolynucleotide that encodes CCR or DHFR (for example mutant DHFR), alsovia IRES sequences or a polynucleotide that encodes a cleavable linker.In a further embodiment, the first polynucleotide encodes the CAR (forexample bispecific CAR) and is linked via IRES sequences or apolynucleotide that encodes a cleavable linker, to a secondpolynucleotide that encodes EGFRt and the first and secondpolynucleotides are linked to a third polynucleotide that encodes CCRand a fourth polynucleotide that encodes DHFR (for example mutant DHFR)via IRES sequences or a polynucleotide that encodes a cleavable linker.Viral vectors are commonly used to carry heterologous genes into cells(e.g., T-cells). Examples of viral vectors which may be used to generategenetically modified cells include but are not limited to SIN lentiviralvectors, retroviral vectors, foamy virus vectors, adeno-associated virus(AAV) vectors and/or plasmid transposons (e.g., sleeping beautytransposon system).

Various methods produce stable transfectants which express the CARs ofthe invention. In one embodiment, a method of stably transfecting andre-directing cells is by electroporation using naked DNA. By using nakedDNA, the time required to produce redirected cells may be significantlyreduced. Additional methods to genetically engineer cells using nakedDNA encoding the CAR of the invention include but are not limited tochemical transformation methods (e.g., using calcium phosphate,dendrimers, liposomes and/or cationic polymers), non-chemicaltransformation methods (e.g., electroporation, optical transformation,gene electrotransfer and/or hydrodynamic delivery) and/or particle-basedmethods (e.g., impalefection, using a gene gun and/or magnetofection).The transfected cells demonstrating presence of a single integratedun-rearranged vector and expression of the CAR may be expanded ex vivo.In one embodiment, the cells selected for ex vivo expansion are CD8⁺ anddemonstrates the capacity to specifically recognize and lyseantigen-specific target cells.

Viral transduction methods may also be used to generate redirected cellswhich express the CAR of the invention. Cell types that may be used togenerate genetically modified cells expressing the bispecific CAR of theinvention include but are not limited to T-lymphocytes (T-cells),natural killer cells, hematopoietic stem cells and/or pluripotentembryonic/induced stem cells capable of giving rise to therapeuticallyrelevant progeny.

Stimulation of the T-cells by an antigen under proper conditions resultsin proliferation (expansion) of the cells and/or production of IL-2. Thecells comprising the CAR of the invention will expand in number inresponse to the binding of one or more antigens to the antigen-specifictargeting regions of the CAR. The invention also provides a method ofmaking and expanding cells expressing a CAR. The method comprisestransfecting or transducing the cells with the vector expressing the CARand stimulating the cells with cells expressing the target antigens,recombinant target antigens, or an antibody to the receptor to cause thecells to proliferate, so as to make and expand T-cells. In anembodiment, the cells may be any one or more of T-lymphocytes (T-cells),natural killer (NK) cells, hematopoietic stem cells (HSCs) orpluripotent embryonic/induced stem cells capable of giving rise totherapeutically relevant progeny.

In an exemplary embodiment, the genetically engineered cells of theinvention express a bispecific CAR which is specific for CD19 and CD20antigens. In a further embodiment, a genetically engineered T-cellexpresses the bispecific CARsCD19scFv-Gly4ser-linker-CD20scFv-hulgG4-hinge-CD28-41BB(cyto)-zeta(cyto)or CD19scFv-Gly4ser-linker-CD20scFv-hulgG4-hingeCH2CH3-CD28tm/cyto-zetaorCD19-Gly4serlinker-CD20scFv-CD8alphahinge-CD8alphaTM-41BBcostim-zetacyto.

In an exemplary embodiment, the invention provides a method of makingand expanding T-cells expressing a CD19-specific and CD20-specific CAR.The method comprises using a lentivirus to transduce CD3xCD28bead-stimulated purified central memory T-cells (such as T-cells fromperipheral blood) with the vector expressing the CD19 and CD20bispecific CAR, growing the T-cells in the presence of rhuIL-2 and/orIL-15 and restimulating the T-cells with CD19⁺ and CD20⁺ cells,recombinant CD19 and CD20, or an antibody to the receptor to cause theT-cells to proliferate, so as to make and expand CD19-specific andCD20-specific T-cells.

Therapeutic Methods of the Invention

The CARs of the invention may be used to overcome therapeutic failuresarising from antigen loss escape variants, to reduce resistance toexisting therapies and/or to treat diseases associated with the antigenstargeted by the CARs.

Accordingly, the invention also provides methods for treating a diseaseassociated with the antigen targeted by the CAR of the invention in asubject in need thereof. The method comprises providing a compositioncomprising the CAR of the invention and administering an effectiveamount of the composition so as to treat the disease associated with theantigen in the subject.

The invention also provides methods for overcoming therapeutic failuresarising from antigen loss escape variants in disease states (e.g.,B-cell diseases) in subjects in need thereof. The method comprisesproviding a composition comprising the CAR of the invention andadministering an effective amount of the composition so as to treat thedisease associated with the antigen in the subject.

In some embodiments, the composition comprises a polynucleotide encodingthe CAR, a protein comprising the CAR or genetically modified cellscomprising the CAR. In another embodiment, the genetically modifiedcells of the composition are T-lymphocytes (T-cells), naïve T cells(T_(N)), memory T cells (for example, central memory T cells (T_(CM)),effector memory cells (T_(EM))), natural killer (NK) cells,hematopoietic stem cells (HSCs) or pluripotent embryonic/induced stemcells capable of giving rise to therapeutically relevant progeny, whichexpress the CAR of the invention. The compositions of the invention maybe administered alone or in conjunction with existing therapies. Ifother therapies are used in conjunction, the compositions of theinvention may be administered concurrently or sequentially with theother the existing therapies.

Pharmaceutical Compositions

In various embodiments, the present invention provides pharmaceuticalcompositions comprising a pharmaceutically acceptable excipient and atherapeutically effective amount of the CAR (for example, bispecificCAR) of the invention. The CAR of the invention in the composition maybe any one or more of a polynucleotide encoding the CAR, a proteincomprising the CAR or genetically modified cells comprising the CAR. Thecomposition may further comprise polynucleotides encoding EGFRt, CCRand/or DHFR (for example mutant DHFR), proteins co-expressed with theCAR including EGFRt, CCR and/or DHFR or genetically modified cells thatexpress the CAR and co-express EGFRt, CCR and/or DHFR. “Pharmaceuticallyacceptable excipient” means an excipient that is useful in preparing apharmaceutical composition that is generally safe, non-toxic, anddesirable, and includes excipients that are acceptable for veterinaryuse as well as for human pharmaceutical use. Such excipients may besolid, liquid, semisolid, or, in the case of an aerosol composition,gaseous.

In various embodiments, the pharmaceutical compositions according to theinvention may be formulated for delivery via any route ofadministration. “Route of administration” may refer to anyadministration pathway known in the art, including but not limited toaerosol, nasal, oral, intravenous, intramuscular, intraperitoneal,inhalation, transmucosal, transdermal, parenteral, implantable pump,continuous infusion, topical application, capsules and/or injections.

The pharmaceutical compositions according to the invention can alsocontain any pharmaceutically acceptable carrier. “Pharmaceuticallyacceptable carrier” as used herein refers to a pharmaceuticallyacceptable material, composition, or vehicle that is involved incarrying or transporting a compound of interest from one tissue, organ,or portion of the body to another tissue, organ, or portion of the body.For example, the carrier may be a liquid or solid filler, diluent,excipient, solvent, or encapsulating material, or a combination thereof.Each component of the carrier must be “pharmaceutically acceptable” inthat it must be compatible with the other ingredients of theformulation. It must also be suitable for use in contact with anytissues or organs with which it may come in contact, meaning that itmust not carry a risk of toxicity, irritation, allergic response,immunogenicity, or any other complication that excessively outweighs itstherapeutic benefits.

The pharmaceutical compositions according to the invention can also beencapsulated, tableted or prepared in an emulsion or syrup for oraladministration. Pharmaceutically acceptable solid or liquid carriers maybe added to enhance or stabilize the composition, or to facilitatepreparation of the composition. Liquid carriers include syrup, peanutoil, olive oil, glycerin, saline, alcohols and water. Solid carriersinclude starch, lactose, calcium sulfate, dihydrate, terra alba,magnesium stearate or stearic acid, talc, pectin, acacia, agar orgelatin. The carrier may also include a sustained release material suchas glyceryl monostearate or glyceryl distearate, alone or with a wax.

The pharmaceutical preparations are made following the conventionaltechniques of pharmacy involving milling, mixing, granulation, andcompressing, when necessary, for tablet forms; or milling, mixing andfilling for hard gelatin capsule forms. When a liquid carrier is used,the preparation will be in the form of syrup, elixir, emulsion or anaqueous or non-aqueous suspension. Such a liquid formulation may beadministered directly p.o. or filled into a soft gelatin capsule.

The pharmaceutical compositions according to the invention may bedelivered in a therapeutically effective amount. The precisetherapeutically effective amount is that amount of the composition thatwill yield the most effective results in terms of efficacy of treatmentin a given subject. This amount will vary depending upon a variety offactors, including but not limited to the characteristics of thetherapeutic compound (including activity, pharmacokinetics,pharmacodynamics, and bioavailability), the physiological condition ofthe subject (including age, sex, disease type and stage, generalphysical condition, responsiveness to a given dosage, and type ofmedication), the nature of the pharmaceutically acceptable carrier orcarriers in the formulation, and the route of administration. Oneskilled in the clinical and pharmacological arts will be able todetermine a therapeutically effective amount through routineexperimentation, for instance, by monitoring a subject's response toadministration of a compound and adjusting the dosage accordingly. Foradditional guidance, see Remington: The Science and Practice of Pharmacy(Gennaro ed. 20th edition, Williams & Wilkins PA, USA) (2000).

EXAMPLES

The following examples are provided to better illustrate the claimedinvention and are not to be interpreted as limiting the scope of theinvention. To the extent that specific materials are mentioned, it ismerely for purposes of illustration and is not intended to limit theinvention. One skilled in the art may develop equivalent means orreactants without the exercise of inventive capacity and withoutdeparting from the scope of the invention.

Example 1

FIG. 1 is a schematic representation of the bispecific chimeric antigenreceptor of the invention. In an exemplary embodiment of the invention,FIG. 2 depicts the components of bispecific anti-CD19xanti-CD20bispecific CAR. FIG. 2 also depicts a schematic of the complete cDNApackaged into epHIV-7 lentivirus vector transfer plasmid. FIGS. 3 and 4show the nucleic and amino acid sequences of an exemplary bispecificCAR, namelyGMCSFss-CD19scFv-Gly4Ser1linker-CD20scFv-IgG4Hinge-CD28tm-41BBzeta-T2A-EGFRt_epHIV7.

Example 2

FIG. 5 is a schematic showing the vector construct of an exemplary CARof the invention, namely, theCD19scFv-CD20scFv-IgG4-CD28tm-CD28costim-CD3zeta transgene construct.The CD 19scFv-CD20scFv-IgG4-CD28tmCD28costim-CD3zeta transgene wasassembled using the one-step isothermal DNA assembly method previouslydescribed by Gibson et. al. (Enzymatic assembly of DNA molecules uptoseveral hindred kilobases. Nature Methods. 2009;6:343-345). The V_(L)and V_(H) domains of the CD19 scFv construct was sequenced from aCD19CAR-CD28-Zeta transgene previously described. Schmitz N, Dreger P,Glass B, Sureda A. Allogeneic transplantation in lymphoma: currentstatus. Haematologica. 2007; 92(11):1533-1548) through polymerase chainreaction (PCR). The V_(H) and V_(L) domains of the CD20 scFv wereassembled by spliced-overlap polymerase chain reaction using aCD20R-CD28-Zeta transgene previously described (Michael Jensen et al.,CD20 is a molecular target for scFvFc:zeta receptor redirected T-cells:implications for cellular immunotherapy of CD20⁺ malignancy. Biology ofBlood and Marrow Transplant. 1998; 4:75-83). The V_(H) and the V_(L)domains of CD19 scFv and CD20 scFv were linked with an 18-residue linkerpeptide as previously described. The IgG4-CD28tm-CD28costim domain wassequenced using the CD19R-CD28-CD3zeta transgene by PCR. TheCD3zeta-T2A-EGFRt_epHIV7 lentiviral destination vector was prepared byNheI and RsrII restriction digestion of the CD19R-CD28 portion from aCD19R-CD28-Zeta-T2A-EGFRt_epHIV7 plasmid previously described (SeitaroTerakura et al., Generation of CD19-CAR modified CD8+ T-cells derivedfrom virus-specific central memory T-cells. Blood. Oct. 26, 2011). Thefinal CD19scFv-CD20scFv-IgG4-CD28tm-CD28costim-CD3zeta construct wasassembled by the one-step isothermal Gibson DNA assembly method usingthe restriction digested Zeta-epHIV7 destination vector and theCD19scFv, CD20scFv, and IgG-4-CD28tm-CD28costim-DNA fragments withprimers for each containing a 30 by overlap at the 5′ terminus.

TABLE 1 Regulatory Elements Present in the bispecific CAR epHIV-7Transfer Plasmid Regulatory Element Function U5 5′ Unique sequence PsiPackaging signal RRE Rev-responsive element flap Contains polypurinetrack sequence and central termination sequence to facilitate nuclearimport of pre-integration complex EF1p Promoter EF1-alpha EukaryoticPromoter sequence driving expression of CD19xCD20 CAR WPRE Woodchuckhepatitis virus derived regulatory element to enhance viral RNAtransportation delU3 3′ U3 with deletion to generate SIN vector R Repeatsequence within LTR U5 3′ U5 sequence in LTR Amp^(R)Ampicillin-resistance gene CoEl ori Replication origin of plasmid SV40ori Replication origin of SV40 CMV promoter CMV promoter to generateviral genome RNA R Repeat sequence within LTR

Example 3

HEK 293T-cells were transfected with anti-CD19xCD20CAR-T2A-EGFRt epHIV-7transfer plasmid or with anti-CD20xCD19CAR-T2A-EGFRt epHIV-7 transferplasmid. Transfected cells were stained with biotinylated anti-Fcantibodies and streptavidin PE (SA-PE) and then were subjected to flowcytometric analysis for detection of expression of the above two CARs.Both the anti-CD19xCD20 CAR and the anti-CD20xCD19 CAR were expressed ontransfected HEK 293T cells.

The epHIV-7 transfer plasmid co-expressed EGFRt with the above twobispecific CARs. EGFRt co-expression was detected on the sametransfected cells using a combination of biotinlylated anti-EGFRantibodies/SA-PE staining and flow cytometric analysis.

Example 4

Primary human peripheral blood derived T-cells were activated with OKT3and then were lentivirally transduced with monospecific anti-CD19 CAR,monospecific anti-CD20 CAR or bispecific anti-CD19xCD20CAR-T2A-EGFRtepHIV7 lentivirus vector. epHIV7 lentivirus vector also encoded EGFRttogether with monospecific anti-CD19 CAR, monospecific anti-CD20 CAR orbispecific anti-CD19xCD20. Thus, cells expressing the CARs co-expressedEGFRt. Transfected cells were stained with biotinlylated anti-EGFRantibodies and SA-PE and then were subjected to flow cytometric analysisfor detection of EGFRt expression and co-expression of monospecific orbispecific CARs. Of the cells transfected with monospecific anti-CD19CAR, 51% expressed EGFRt; of the cells transfected with monospecificanti-CD20 CAR, 38.5% expressed EGFRt; of the cells transfected with thebispecific anti-CD19xCD20 CAR, 63.8% expressed EGFRt.

T cell receptor (TCR) complex in transfected cells was also detected inthe same transfected cells using FITC-conjugated anti-TCRα and anti-TCRβantibodies staining and flow cytometric analysis.

Example 5

H9 cells were genetically modified to express CD19, or CD20, or bothCD19 and CD20. Cells were stained with anti-CD19 and anti-CD20antibodies and then were subject to flow cytometric analysis to detectthe expression of CD19 and CD20. Cytometric analysis confirmed thedesired expression profile of CD19⁺CD20⁻, CD19⁻CD20⁺, and CD19⁺CD20⁺ H9cells, namely, genetically engineered H9 cells expressed CD19, or CD20,or both CD19 and CD20 thereby simulating cancer target cells, whichcontain antigen-negative antigen loss escape variants. As describedlater, these cell lines were subsequently used as target cells tostimulate CAR-expressing T-cell lines, which act as effector cells tokill target cells.

Also, endogenous levels of CD19 and CD20 expression in SUP-B15 and DHL-6cell lines was analyzed using anti-CD19 APC and anti-CD20 PE stainingand flow cytometric analysis. SUP-B15 cell line expressed high level ofCD19 with low level of CD20 (thus CD19⁺CD20⁻), and DHL-16 cell lineexpressed high level of CD20 with low level of CD19 (thus CD19⁻CD20⁺).

Example 6

A 4-hour chromium release assay was used to measure the lysis of thetarget cells by the effector cells. Effector cells are primary humanT-cells lentivirally transduced to express monospecific anti-CD19 CAR,monospecific anti-CD20 CAR or bispecific anti-CD19xCD20 CAR. Thebispecific anti-CD19xCD20 CAR effector T-cells effectively lysed allCD19⁺CD20⁻, CD19⁻CD20⁺, and CD19⁺CD20⁺ target cells, which includeCD19⁺CD20⁻ H9 cells, CD19⁻CD20⁺ H9 cells, CD19⁺CD20⁺ H9 cells andSUP-B15 cells. At effector to target ratios of 1:1, 3:1, 10:1, and 30:1,about 25%, 45%, 50% and 60%, respectively, target cells were lysed.

In contrast, monospecific CAR expressing T-cell lines fail to lyseantigen-negative antigen loss escape variants, which escaped from themonospecific CAR effector cells. The anti-CD 19 CAR effector T-cellsfailed to lyse CD19⁻CD20⁺ targets and the anti-CD20 CAR effector T-cellsfailed to lyse CD19′CD20⁻ targets.

Example 7

Bispecific CAR-expressing CD4 enriched T-cells were activated forcytokine secretion (Interferon gamma (IFN-g, IFN-γ)) upon stimulation byCD19⁺CD20⁻, CD19⁻CD20⁺, and CD19⁺CD20⁺ target cells, which includeCD19⁺CD20⁻ H9 cells, CD19⁻CD20⁺ H9 cells, CD19⁺CD20⁺ H9 cells andSUP-B15 cells. IFN-γ content was measured by cytokine bead array ofculture supernatants of T-cells and target cells after 24-hours ofco-culture. Activated bispecific CAR-expressing CD4 enriched T-cellssecreted at least 2500 pg/ml INF-g upon stimulation by every type oftarget cells. In contrast, monospecific CAR expressing T-cell lines werenot activated for cytokine INF-g secretion upon stimulation byantigen-negative antigen loss escape variants, which escaped from themonospecific CAR effector cells. CD19 CAR T-cells failed to secreteIGN-γ upon co-culture with CD19⁻CD20⁺ target cells and CD20 CAR T-cellsfailed to secrete IGN-γ upon co-culture with CD19⁺CD20⁻ target cells.

In-vitro Stimulation Assay Stimulators (3 × 10{circumflex over ( )}5):TM-LCL H9 parent OKT3-TM-LCL H9 CD19R SUP-B15 H9 CD20R DHL-6 H9 CD19/20RResponders (1 × 10{circumflex over ( )}6 on S₁R₂D₁₇): CD4 enriched mockCD8 enriched mock CD4 enriched CD19R CD8 enriched CD19R CD4 enrichedCD20R CD8 enriched CD20R CD4 enriched CD19/20R CD8 enriched CD19/20RCells incubated for 24 hrs, and cell free supernatant will be harvestedtoday for BioPlex assay

Example 8

The example below describes a CD19 specific chimeric antigen receptorlinked to truncated epidermal growth factor receptor (EGFRt) via a T2Asequence. EGFRt may be linked to and co-expressed with other chimericantigen receptors, for example, bispecific chimeric antigen receptors.

Applicants demonstrated the utility of such a truncated EGFR (huEGFRt)expressed by transduced T cells for immunomagnetic purification usingbiotinylated cetuximab, cell tracking by flow cytometry andimmunohistochemistry, and in vivo cell ablation after systemic cetuximabadministration. In this exemplary embodiment, domain I and II of EGFRthave been deleted while domains III and IV have been retained.

The CD19CAR-T2A-EGFRt-epHIV7 lentiviral construct contains: (1) thechimeric antigen receptor (CAR) sequence consisting of the V_(H) andV_(L) gene segments of the CD19-specific FMC63 monoclonal antibody(mAb), an IgG4 hinge-C_(H2)-C_(H3), the transmembrane, and cytoplasmicsignaling domains of the co-stimulatory molecule CD28, and thecytoplasmic domain of the CD370 chain (Kowolik C K. et al., CD28costimuation provided through a CD19-specific chimeric antigen receptorenhances in vivo persistence and antitumor efficacy of adoptivelytransferred T cells. Cancer Res. 2006, 66(22):10995-11004); (2) theself-cleaving T2A sequence (Szymczak AL. et al., Correction ofmulti-gene deficiency in vivo using a “self-cleaving” 2A peptide-basedretroviral vector. Nat Biotechnol 2004; 22(5)589-594); and (3) thetruncated EGFR sequence as indicated.

Immunomagnetic Enrichment of huEGFRt⁺ Human T Cells After LentiviralTransduction

The biotinylated cetuximab was used for either immunomagnetic selectionor FACS sorting of huEGFRt⁺ cells. Applicants used biotinylatedcetuximab in conjunction with commercially available antibiotinmicrobeads for the immunomagnetic selection of human T cells transducedwith a self-inactivating lentivirus that directs the co-expression ofCD19CAR and huEGFRt.

PBMCs or purified central memory (CD45RO⁺CD62L⁺ T_(CM)) or effectormemory (CD45RO⁺CD62L⁺ T_(EM)) T-cell subsets were stimulated withanti-CD3/anti-CD28 beads and then transduced by lentiviral vector togenerate a panel of primary human T-cell lines, of which 2.6%-40%expressed huEGFRt and CAR. The unselected cells were labeled withbiotinylated cetuximab and anti-biotin microbeads; and then wereseparated to consistently obtain a selected cell population, of which90% express huEGFRt and CAR.

Unselected T cells and selected fraction were stained withbiotinylated-cetuximab and either PE-conjugated streptavidin orPE-conjugated anti-biotin Ab, and then were subject to flow cytometricanalysis. Selection of CD19CAR⁺EGFRt⁺ cells was performed either 3 daysafter transduction of OKT3 blasts (enriched from 38% to 98%), or after 1rapid expansion cycle of transduced effector memory CD62LCD45R⁺-derivedcells (enriched from 20% to 96%), after 3 rapid expansion cycles oftransduced CMVpp65-specific TCM-derived cells (enriched from 12% to91%), or after 2 rapid expansion cycles of transduced CD8⁺TCM-derivedcells (enriched from 3% to 97%). Selection of CD19CAR⁺EGFRt⁺IMPDH2dm⁺cells was performed after 1 rapid expansion cycle of transducedTCM-derived cells (enriched from 25 to 92%).

CD19CAR-T2A-EGFRt-IMPDH2dm constructs contained in lentiviral vectorsinclude codon optimized sequence portions of the CD19-specific, CD28co-stimulatory CAR (CD19CAR), followed by the self-cleavable T2A, andselection markers huEGFRt and IMPDH2dm (a double mutant of the inosinemonophosphate dehydrogenase 2 gene that allows for cell survival uponaddition of mycophenolate 27), along with the Elongation Factor 1promoter sequences (EF-1p), the GM-CSF receptor alpha chain signalsequences (GMCSFRss), and the 3 nucleotide stop codon.

Before immunomagnetic selection, a proliferative advantage of huEGFRt⁻cells over huEGFRt⁺ cells was observed in cultures of unselectedtransduced T cells subjected to OKT3-mediated expansion. However, afterimmunomagnetic selection, the level of huEGFRt expression and thefrequency of expressing cells remained stable over 3 consecutive 14-daycycles of OKT3-based expansion¹⁴. The fold expansion of EGFRt⁺ cellsafter immunomagnetic selection was significantly enhanced over that ofhuEGFRt⁺ cells in the unselected cultures.

These data demonstrate that huEGFRt can serve as a cell surface markerunique to transduced human T cells and enable subsequent cetuximab-basedimmunomagnetic purification of stable huEGFRt-expressing cellpopulations which also express CARs.

Tracking of Adoptively Transferred huEGFRt⁺ T Cells Using Flow Cytometryand Immunohistochemistry

To test the utility of huEGFRt for tracking the engraftment ofadoptively transferred T cells, Applicants harvested blood and bonemarrow specimens from NOD/Scid IL-2RγC^(null) mice engrafted withCD19CAR⁺EGFRt⁺ human T cells.

First, unfixed peripheral blood and bone marrow mononuclear cell sampleswere subjected to flow cytometric analysis after being stained withbiotinylated cetuximab and PE-conjugated streptavidin. Although thelevel of human CD45⁺ T-cell engraftment (20%-25%) was similar in animalsadministered either EGFRt-negative or -positive T cells, double stainingfor human CD45 and EGFR allowed for the resolution of huEGFRt⁺ (ie,transgeneexpressing) human T cells from their huEGFRt-negativecounterparts.

Second, Applicants sought to determine whether standard paraffinembedded fixed tissue specimens were amenable to detection of huEGFRt⁺T-cell infiltrates using EGFR-specific diagnostic kits. Applicantsperformed immunohistochemical analysis of paraffin-embedded femurs fromengrafted mice and detected huEGFRt⁺ cells in the bone marrow. Thesedata support the utility of huEGFRt to serve as a tracking marker forquantifying the frequency and tissue distribution of adoptivelytransferred T cells.

Cetuximab Binding to huEGFRt Sensitizes Human T Cells to ADCC

A valuable feature of a cell surface selection/tracking marker would beits capacity to serve as a target for in vivo cell ablation. Applicantsevaluated the extent to which Cetuximab bound to huEGFRt on T cellsactivates ADCC of huEGFRt⁺ T cells in vitro, and whether Cetuximabadministration could attenuate the engraftment of adoptively transferredhuEGFRt⁺ T cells in NOD/scid mice.

⁵¹Cr-labeled huEGFRt⁺ T cells as the target cells and human GM-CSFactivated fresh PBMCs as effectors were co-cultured. Then, the additionof Cetuximab specifically sensitized huEGFRt⁺ T cells to ADCC cytolysisby effectors. Lysis of huEGFRt⁺ T cells was measured by 4-hour chromiumrelease assay and results showed that Cetuximab addition significantlyincreased lysis from less than 5% to about 50%, 45%, 40% and 15%respectively at effector to target (effector:target) ratios 50:1, 25:1,5:1 and 1:1.

In contrast, the addition of the CD20-specific mAb Rituxan had no effecton triggering ADCC of huEGFRt⁺ T cells in this assay.

Applicants next derived huEGFRt⁺ CTLL-2 murine T cells that wereadditionally modified to secrete autocrine IL-2 and express the fireflyluciferase biophotonic reporter, and adoptively transferred theseffLuc⁺huEGFRt⁺ CTLL-2 cells via intravenous injection to NOD/scid mice,which subsequently received Cetuximab or Rituxan. The in vivoengraftment of transferred CTLL-2, as measured by in vivo biophotonicimaging, was significantly inhibited (97%, P<0.05) in mice that receivedErbitux (1 mg intraperitoneally daily). The Cetuximab-mediatedelimination of the ffLuc⁺huEGFRt⁺ CTLL-2 cells occurred between 4 and 6days. These data support the use of Cetuximab administration as atherapeutic control for patients receiving huEGFRt⁺ T cells.

Example 9

This example describes T cells with an intrinsic γc cytokine signalingmechanism, and shows that chimeric cytokine receptors (CCR) IL-2/IL-15Rβ(CγCR2) and IL-7Rα (CγCR7) have the ability to improve the survival,persistence, and in vivo engraftment of cytotoxic T cells (CTLs).Truncated CD19 antigen (CD19t) was linked to CγCR via a T2A linker toshow the expression of CγCR on the cell surface. The chimeric cytokinereceptors described herein may be linked to the chimeric antigenreceptors of the invention, such as bispecific CARs described herein.

To develop a cell-intrinsic, ligand-independent γc cytokine platform,Applicants engineered chimeric γc cytokine receptors (CγCR) comprised ofthe IL-7 cytokine tethered by ten amino acids to the extracellulardomain of IL-7Rα. To engineer a CγCR that confers an IL-7R signal, IL-7cytokine was tethered to the full length IL-7Rα chain (CγCR7). A CγCRthat provides an IL-2/IL-15Rβ signal was engineered by tethering theIL-7 cytokine to the extracellular and transmembrane domain of IL-7Rαfused to the cytoplasmic domain of IL-2/IL-15Rβ (CγCR2). These singlechain chimeric receptors are expected to require endogenous γc chain forsignaling.

Constructs were then generated where the CγCR transgenes were followedby the self-cleavable T2A sequence, and a cytoplasmically truncated CD19antigen (CD19t). CγCR and CD19t are expressed as a single transcript andcleaved post-translationally at the C-terminus of the T2A self-cleavingpeptide to yield two separate type 1 membrane proteins CγCR(T2A) andCD19t. Based on expression of two proteins from a single transcript, theratio of CγCR(T2A) to CD19t expression is 1:1, therefore, cell surfaceCD19t is an indication of CγCR cell surface expression. Lentiviraltransduction and expression of these constructs could then be measuredby surface CD19t expression, such as that seen in both Jurkat and NK-92cell lines.

A third CγCR was also engineered, having IL-7 cytokine tethered to atruncated IL-7Rα (CγCR7t), which is missing amino acids 1-126 from theextracellular domain of the IL-7Rα. A molecular model of CγCR7tdimerization with the endogenous γc chain is necessary for signaltransduction. The lack of amino acids 1-126 of the extracellular domainof IL-7Rα renders the CγCR7t nonfunctional.

Truncated CγCR7 expression does not functionally signal or supportcytokine independent cell growth. Flow cytometric detected cell-surfaceCD19t on lenti-transduced Jurkat (95% CD19t⁺CγCR7t⁺) and Teff cell lines(97% CD19t⁺CγCR7t⁺). Western blot analysis of STAT5 phosphorylationwithin CγCR7t expressing Jurkat cell line did not detect obviousincrease of phosphorylated STAT5 as compared to non-transduced controlJurkat cell line. Positive controls OKT3 stimulated PBMC cultured in 50U/ml IL-2 and 10 ng/ml IL-15 and K562 showed activation of increasedphosphorylated STAT5. Accordingly, expansion and viability of CTLstransduced with CγCR7t cultured for 20 days were still dependent oncytokines

To determine if functional CγCRs such as CγCR2 and CγCR7 could supportthe growth of CD8⁺ human primary T cells in the absence of exogenouscytokine, we measured the expansion of CTLs expressing each CγCR. Humanprimary T cells expressing CγCR7t were unable to expand in the absenceof exogenous cytokine. Both CγCR2 and CγCR7 were able to support thesurvival and proliferation of the CD8⁺ T cells through maintenance ofviability, in a manner similar to that of parental cells cultured in 5U/ml and 0.5 U/ml IL-2, respectively. The increased total cell expansionmeasured for CγCR2⁺ versus CγCR7⁺ CTL correlates with increasedexpression (i.e., MFI of 26 for CγCR7 versus 52 for CγCR2) of Ki67, anuclear antigen protein present in G1, S, G2, and M phase of the cellcycle. Higher Bcl-2, an key antiapoptotic protein induced in response toIL-2 and IL-7 signaling, expression was observed for CγCR7⁺ versusCγCR2⁺ CTL, supporting the ability of CγCR7 to maintain the survival ofthe human primary T cells. Together this data suggests that, althoughboth CγCRs support cytokine-independent T cell viability and expansion,CγCR2 provides a proliferative advantage while CγCR7 maintains survivalfor effector CD8⁺ CTLs.

CγCR Expressing CD8⁺ T Cells Exhibit Cytokine Independent Engraftment inVivo

Studies by our lab and others indicate that human CTL engraftment inNOD/Scid IL-2RγC^(null) mice is dependent on exogenous administration ofhuman IL-15 or IL-2. To test the potential of CγCR expression in CTLs toovercome this dependence, parental effector T cells, CγCR7⁺ CTLs, andCγCR2⁺ CTLs were injected into the tail vein of immunodeficient NOD/ScidIL-2RγC^(null) mice in the absence of exogenous cytokine administration.Total engraftment was compared by harvesting at least four mice pergroup at day 8, 17, 24, and 48 and analyzing T cell levels in the bloodand bone marrow.

In the blood, CγCR2⁺ CTLs had impressive significant (P<0.007) exogenouscytokine independent engraftment compared to CγCR7⁺ CTLs and theparental cells. In the bone marrow, both CγCR7⁺ CTLs (P<0.03) and CγCR2⁺CTLs (P<0.0005) had significant exogenous cytokine independentengraftment compared to the parental cells. CγCR2⁺ CTLs had higherengraftment compared to CγCR7⁺ CTLs. This indicates that both CγCR7³⁰CTLs and CγCR2⁺ CTLs are capable of supporting exogenous cytokineindependent engraftment but the total percentage of cells was different.The blood supported higher percent engraftment of CγCR2⁺ CTLs comparedto bone marrow. The bone marrow supported the engraftment of CγCR7⁺ CTLsover a longer period of time. Importantly, the engraftment was notinfinite as the cells were no longer present in the blood and bonemarrow at day 48 in either group.

Cell intrinsic γc cytokine signals can replace the need for exogenouscytokine administration for the support of adoptively transferred CTLs.Providing cell intrinsic cytokine receptors can overcome the majorlimitation of adoptive immunotherapy; the long-term persistence ofadoptively transferred CTL. This may eliminate the need foradministration of exogenous cytokine, which may reduce toxicities andbystander effects on endogenous cell types.

Example 10

This example shows that CD19 chimeric antigen receptor linked to EGFRtand DHFR can be regulated by methotrexate. Using the methods describedherein, the dihydroxyfolate receptor described herein may be linked tothe bispecific chimeric antigen receptors of the invention.

Applicants developed a human selectable transgene using a variant ofhuman dihydrofolate reductase (hDHFR) that would enable selection of Tcells with the less toxic, pharmaceutically available drug methotrexate(MTX). MTX exerts its anti-proliferative effect through competitiveinhibition of DHFR, a key enzyme essential for de novo synthesis ofthymidylate nucleotides.

In the instant example, Applicants evaluated the potential of DHFR^(FS)(hDHFR L22F/F31S variant) mediated in vitro selection of primary human Tcells that co-express a CD19-specific chimeric antigen receptor (CD19CARfor targeting of CD19-expressing tumors). In this strategy, wehypothesized that exposure of a transduced mixed population of T cellsto the lymphotoxic drug MTX should lead to elimination of untransduced Tcells and selective expansion of DHFR^(FS)/CD19CAR T cells co-expressingT cells, increasing the anti-tumor efficacy of the T cell population asa whole. Here Applicants show that DHFR^(FS)-mediated selection of genemodified T cells enforced the CD19CAR therapeutic transgene expression,and allowed for the derivation of CAR⁺ stable integrants in the presenceof clinically attainable concentrations of MTX (e.g., 0.1 μM MTX).

To translate the hDHFR^(FS) selection approach for potential therapeuticutility, Applicants designed a lentiviral vector co-expressinghDHFR^(FS) in conjunction with a CD19-specific chimeric antigen receptor(CD19CAR) and a truncated human EGFR polypeptide as a tracking marker(huEGFRt) each separated by a ribosomal skip T2A sequence.

CTLL2 T cells were first transduced with this CD19CAR-huEGFRt-hDHFR^(FS)lentiviral vector and evaluated for their resistance to MTX. Ten daysafter lenti-transduction, 7-8% of the cells were positive for CD19CARand huEGFRt expression.

In the absence of MTX, the non-transduced and transduced CTLL2 cellsexpanded at an equivalent rate (21- and 27-fold respectively). Afterincubation with MTX (0-0.1 μM) for 8 days, a 7-fold expansion with 80%survival was observed with transduced cells, while exposure ofnon-transduced CTLL2 cells to ≧0.05 μM MTX resulted in strong inhibitionof non-transduced CTLL2 cell expansion and viability.

Evaluation of huEGFRt expression levels of transduced CTLL2 cells after8 days in culture with varying concentrations of MTX further revealedsignificant MTX-mediated enrichment of transgene-expressing huEGFRtcells (49%, 93%, 98.5%, 99% at 0.01, 0.025, 0.05 and 0.1 μM MTXrespectively).

To further characterize the maximum dose of MTX that could be toleratedby selected CTLL2 cells, transduced CTLL2 cells that had been culturedin 0.1 μM MTX for 8 days were re-plated at a wider range of MTXconcentrations (up to 0.75 μM). These transduced and pre-MTX selectedcells were able to expand 90-100 fold at MTX concentrations up to 0.25μM, which is equivalent to non-transduced control CTLL2 expansion in theabsence of MTX.

Applicants transduced primary human T cells with the sameCD19CAR-huEGFRt-hDHFR^(FS) lentiviral vector. Purified CD62L⁺CD45RO⁺ Tcells were used as a starting population based on their potential forpersistence after adoptive transfer. Ten days after transduction, theseT cells were cultured in varying concentrations of MTX and assessed forcell number and viability over time. After 10 days, transduced andnon-transduced T cells expanded equally (80-fold) in the absence of MTX.Furthermore, even at 0.1 μM MTX, transduced T cells maintained aviability of 63%, while non-transduced primary human T cells exhibitedstrong inhibition of both viability and fold-expansion starting atconcentrations as low as 0.025 μM MTX.

Flow cytometric evaluation of transduced T cells after 10 days inculture with varying concentrations of MTX revealed significantMTX-mediated enrichment of transgene-expressing cells (e.g., 0.025 μMMTX enriched about 54% CD19CAR⁺ and 79% EGFRt⁺; 0.05 μM MTX enrichedabout 76% CD19CAR⁺ and 89% EGFRt⁺)

Comparison of CD19CAR and EGFRt expression at day 6 vs. day 10 ofculture revealed the steady progression of this MTX/DHFR^(FS)-mediatedselection over time (Day 0: 18% CD19CAR⁺, 28% EGFRt⁺; Day 6: 48%CD19CAR⁺, 71% EGFR⁺; Day 10: 70% CD19CAR⁺, 88% EGFRt⁺).

All references cited herein are incorporated by reference in theirentirety as though fully set forth. Unless defined otherwise, technicaland scientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. Singleton et al., Dictionary of Microbiology and MolecularBiology 3^(rd) ed., J. Wiley & Sons (New York, N.Y. 2001); March,Advanced Organic Chemistry Reactions, Mechanisms and Structure 5^(th)ed., J. Wiley & Sons (New York, N.Y. 2001); and Sambrook and Russel,Molecular Cloning: A Laboratory Manual 3rd ed., Cold Spring HarborLaboratory Press (Cold Spring Harbor, N.Y. 2001), provide one skilled inthe art with a general guide to many of the terms used in the presentapplication.

One skilled in the art will recognize many methods and materials similaror equivalent to those described herein, which could be used in thepractice of the present invention. Indeed, the present invention is inno way limited to the methods and materials described. For purposes ofthe present invention, the following terms are defined below.

While these descriptions directly describe the above embodiments, it isunderstood that those skilled in the art may conceive modificationsand/or variations to the specific embodiments shown and describedherein. Any such modifications or variations that fall within thepurview of this description are intended to be included therein as well.Unless specifically noted, it is the intention of the inventors that thewords and phrases in the specification and claims be given the ordinaryand accustomed meanings to those of ordinary skill in the applicableart(s).

The foregoing description of various embodiments of the invention knownto the applicant at this time of filing the application has beenpresented and is intended for the purposes of illustration anddescription. The present description is not intended to be exhaustivenor limit the invention to the precise form disclosed and manymodifications and variations are possible in the light of the aboveteachings. The embodiments described serve to explain the principles ofthe invention and its practical application and to enable others skilledin the art to utilize the invention in various embodiments and withvarious modifications as are suited to the particular use contemplated.Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed for carrying out the invention.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art that,based upon the teachings herein, changes and modifications may be madewithout departing from this invention and its broader aspects. It willbe understood by those within the art that, in general, terms usedherein are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.).

What is claimed is:
 1. A bispecific chimeric antigen receptor,comprising: a. at least two antigen-specific targeting regions; b. anextracellular spacer domain; c. a transmembrane domain; d. at least oneco-stimulatory domain; and e. an intracellular signaling domain, whereineach antigen-specific targeting region comprises an antigen-specificsingle chain Fv (scFv) fragment, and binds a different antigen, andwherein the bispecific chimeric antigen receptor is co-expressed with atherapeutic control.
 2. The chimeric antigen receptor of claim 1,wherein the therapeutic control comprises any one or more of truncatedepidermal growth factor receptor (EGFRt), thymidine kinase, cytosinedeaminase, nitroreductase, xanthine-guanine phosphoribosyl transferase,human caspase 8, human caspase 9, purine nucleoside phosphorylase, acomponent of the linamarase/linamarin/glucose oxidase system,deoxyribonucleoside kinase, a component of the horseradish peroxidase(HRP)/indole-3-acetic acid(IAA) system, Gamma-glutamylcysteinesynthetase, a component of the CD20/alphaCD20 system, CD34/thymidinekinase chimera, dox-depedent caspase-2, mutant thymidine kinase(HSV-TKSR39), a component of the AP1903/Fas system, a chimeric cytokinereceptor (CCR), a selection marker, and combinations thereof.
 3. Thebispecific chimeric antigen receptor of claim 2, wherein the therapeuticcontrol comprises the EGFRt, which binds any one or more of anEGFR-specific siRNA, a small molecule, and an anti-EGFR antibody or afragment thereof, -and combination thereof.
 4. The bispecific chimericantigen receptor of claim 2, wherein the therapeutic control comprisesthe selection marker, which comprises any one or more of dihydroxyfolatereceptor (DHFR), mutant DHFR, methylated-DNA-protein-cysteinemethyltransferase, inosine monophosphate dehydrogenase II (IMDHP2) andcombinations thereof.
 5. The bispecific chimeric antigen receptor ofclaim 2, wherein the therapeutic control comprises the CCR, whichcomprises any one or more of (i) IL-7cytokine-linker- IL7Rα, (ii) IL-7cytokine-linker-extracellular domain of IL-7Rα-transmembrane domain ofIL-7Rα-cytoplasmic domain of IL-2Rβ, (iii) IL-7 cytokine linker-IL2Rβ,and (iv) combinations thereof.
 6. The bispecific chimeric antigenreceptor of claim 1, wherein the bispecific chimeric antigen receptorand the therapeutic control are expressed from a nucleic acid comprisinga nucleotide sequence encoding the bispecific chimeric antigen receptorand a nucleotide sequence encoding the therapeutic control, linked via anucleotide sequence encoding a cleavable linker.
 7. The bispecificchimeric antigen receptor of claim 6, wherein the cleavable linkercomprises a self-cleaving cleavable linker.
 8. The bispecific chimericantigen receptor of claim 7, wherein the cleavable linker is any one ormore of a 2A linker, 2A-like linker and functional equivalents thereof.9. The bispecific chimeric antigen receptor of claim 1, wherein theextracellular spacer domain comprises any one or more of an Fc fragmentof an antibody or a functional equivalent, or fragment thereof, a hingeregion of an antibody or a functional equivalent, fragment or thereof, aCH2 region of an antibody, a CH3 region of an antibody, an artificialspacer sequence or combinations thereof.
 10. The bispecific chimericantigen receptor of claim 9, wherein the extracellular spacer domaincomprises any one or more of (i) a hinge, CH2 and CH3 region of IgG4,(ii) a hinge region of IgG4, (iii) a hinge and CH2 region of IgG4, (iv)a hinge region of CD8α, (v) a hinge, CH2 and CH3 region of IgG1, (vi) ahinge region of IgG1, (vi) a hinge and CH2 region of IgG1, and (vii)combinations thereof.
 11. The bispecific chimeric antigen receptor ofclaim 1, wherein the transmembrane domain comprises any one or more of atransmembrane region of a Type I transmembrane protein, an artificialhydrophobic sequence, and combinations thereof.
 12. The bispecificchimeric antigen receptor of claim 11, wherein the transmembrane domaincomprises any one or more of a transmembrane domain of a zeta chain of aT cell receptor complex, CD28, CD8α, and combinations thereof.
 13. Thebispecific chimeric antigen receptor of claim 1, wherein theco-stimulatory domain comprises a signaling domain from any one or moreof CD28, CD137 (4-1BB), CD134 (OX40), Dap10, CD27, CD2, CD5, ICAM-1,LFA-1, Lck, TNFR-I, TNFR-II, Fas, CD30, CD40 and combinations thereof.14. The bispecific chimeric antigen receptor of claim 1, wherein theintracellular signaling domain comprises a signaling domain of one ormore of a human CD3 zeta chain, FcγRIII, FcεRI, a cytoplasmic tail of aFc receptor, an immunoreceptor tyrosine-based activation motif (ITAM)bearing cytoplasmic receptors, and combinations thereof.
 15. Thebispecific chimeric antigen receptor of claim 1, wherein each of the atleast two antigen-specific targeting domains target an antigenindependently selected from the group consisting of antigens specificfor cancer, an inflammatory disease, a neuronal disorder, diabetes, acardiovascular disease, an infectious disease, an autoimmune disease,and combinations thereof.
 16. The bispecific chimeric antigen receptorof claim 15, wherein the antigen specific for cancer comprises any oneor more of 4-1BB, 5T4, adenocarcinoma antigen, alpha-fetoprotein, BAFF,B-lymphoma cell, C242 antigen, CA-125, carbonic anhydrase 9 (CA-IX),C-MET, CCR4, CD152, CD19, CD20, CD200, CD22, CD221, CD23 (IgE receptor),CD28, CD30 (TNFRSF8), CD33, CD4, CD40, CD44 v6, CD51, CD52, CD56, CD74,CD80, CEA, CNTO888, CTLA-4, DRS, EGFR, EpCAM, CD3, FAP, fibronectinextra domain-B, folate receptor 1, GD2, GD3 ganglioside, glycoprotein75, GPNMB, HER2/neu, HGF, human scatter factor receptor kinase, IGF-1receptor, IGF-I, IgG1, L1-CAM, IL-13, IL-6, insulin-like growth factor Ireceptor, integrin α5β1, integrin αvβ3, MORAb-009, MS4A1, MUC1, mucinCanAg, N-glycolylneuraminic acid, NPC-1C, PDGF-R α, PDL192,phosphatidylserine, prostatic carcinoma cells, RANKL, RON, ROR1, SCH900105, SDC1, SLAMF7, TAG-72, tenascin C, TGF beta 2, TGF-β, TRAIL-R1,TRAIL-R2, tumor antigen CTAA16.88, VEGF-A, VEGFR-1, VEGFR2, vimentin,and combinations thereof.
 17. The bispecific chimeric antigen receptorof claim 1, wherein the at least two antigen-specific targeting regionsbind (i) CD19 and CD20, (ii) CD20 and L1-CAM, (iii) L1-CAM and GD2, (iv)EGFR and L1-CAM, (v) CD19 and CD22, (vi) EGFR and C-MET, (vii) EGFR andHER2, (viii) C-MET and HER2, or (ix) EGFR and ROR1.
 18. The bispecificchimeric antigen receptor of claim 1, wherein the at least twoantigen-specific targeting regions bind CD19 and CD20.
 19. Thebispecific chimeric antigen receptor of claim 15, wherein the antigenspecific for an inflammatory disease comprises any one or more of AOC3(VAP-1), CAM-3001, CCL11 (eotaxin-1), CD125, CD147 (basigin), CD154(CD40L), CD2, CD20, CD23 (IgE receptor), CD25 (α chain of IL-2receptor), CD3, CD4, CD5, IFN-α, IFN-γ, IgE, IgE Fc region, IL-1, IL-12,IL-23, IL-13, IL-17, IL-17A, IL-22, IL-4, IL-5, IL-5, IL-6, IL-6receptor, integrin α4, integrin α4β7, Lama glama, LFA-1 (CD11a),MEDI-528, myostatin, OX-40, rhuMAb β7, scleroscin, SOST, TGF beta 1,TNF-α, VEGF-A, and combinations thereof.
 20. The bispecific chimericantigen receptor of claim 15, wherein the antigen specific for aninfectious disease comprises any one or more of anthrax toxin, CCR5,CD4, clumping factor A, cytomegalovirus, cytomegalovirus glycoprotein B,endotoxin, Escherichia coli, hepatitis B surface antigen, hepatitis Bvirus, HIV-1, Hsp90, Influenza A hemagglutinin, lipoteichoic acid,Pseudomonas aeruginosa, rabies virus glycoprotein, respiratory syncytialvirus, TNF-α, and combinations thereof.
 21. The bispecific chimericantigen receptor of claim 1, wherein each of the at least twoantigen-specific-targeting regions independently binds to a Bcell-specific antigen and/or an antigen expressed by a B cell-associateddisease, a B lineage malignancy, and/or a cancerous B cell.
 22. Thebispecific chimeric antigen receptor of claim 21, wherein each of the atleast two antigen-specific targeting regions independently binds to anantigen selected from the group consisting of CD19, CD20 and CD22. 23.The bispecific chimeric antigen receptor of claim 22, wherein at leastone of the at least two antigen-specific targeting regions specificallybinds to a CD19.
 24. The bispecific chimeric antigen receptor of claim22, wherein the at least two antigen-specific targeting regions bindCD19 and CD22.
 25. A bispecific chimeric antigen receptor, comprising:a. at least two antigen-specific targeting regions; b. an extracellularspacer domain; c. a transmembrane domain; d. at least one co-stimulatorydomain; and e. an intracellular signaling domain, wherein eachantigen-specific targeting region comprises an antigen-specific singlechain Fv (scFv) fragment, and binds a different antigen, and wherein thebispecific chimeric antigen receptor is co-expressed with truncatedepidermal growth factor receptor (EGFRt).
 26. A bispecific chimericantigen receptor, comprising: a. at least two antigen-specific targetingregions; b. a CD8α hinge extracellular spacer domain; c. a CD8αtransmembrane domain; d. a 4-1BB co-stimulatory domain; and e. a CD3zeta intracellular signaling domain, wherein each antigen-specifictargeting region comprises an antigen-specific single chain Fv (scFv)fragment, and binds a different antigen, wherein the bispecific chimericantigen receptor is co-expressed with truncated epidermal growth factorreceptor (EGFRt), and wherein the bispecific chimeric antigen receptorand EGFRt are linked via a T2A linker.
 27. A bispecific chimeric antigenreceptor-encoding polynucleotide, the polynucleotide comprising: a. anucleic acid encoding (i) at least two antigen-specific targetingregions that bind at least two different antigens, each of said regionsindividually comprising an scFv, (ii) an extracellular spacer domain,(iii) a transmembrane domain, (iv) a co-stimulatory domain, and (v) anintracellular signaling domain; and b. a nucleic acid encoding atherapeutic control.
 28. A genetically engineered cell comprising a. abispecific chimeric antigen receptor-encoding polynucleotide comprisinga nucleic acid encoding (i) at least two antigen-specific targetingregions that bind at least two different antigens, each of said regionsindividually comprising an scFv, (ii) an extracellular spacer domain,(iii) a transmembrane domain, (iv) a co-stimulatory domain, and (v) anintracellular signaling domain; and b. a polynucleotide encoding atherapeutic control.